Explanation of symbol for characters Tuli Rafi Activity: Let us discuss with friends and teachers and solve the problem. Exercise: Let us think logicaly and solve. If needed, let us discuss with friends and take help from the teacher. Let us do: Let us solve it by ourselves. Key question: Let us solve the problem together. 1. Characters: In the textbook two young learners Tuli and Rafi are making conversation with each other. Through their discussions and opinions the concept of Mathematics has been made clear. 2. In the lessons a few symbols are used to show the steps.

1 Numbers and place values Read numbers and write in words (21 to 100) 1 count 8 Comparison of numbers 14 Place value 17 Comparison of numbers (using place values) 22 Even-odd numbers and number patterns 25 Ordinal number 34 2 Addition and Subtraction (Without carry) Addition (1) 40 Subtraction (1) 46 Mathematical Relation (Addition and subtraction) 53 Addition (2) 55 Subtraction (2) 64 Problems related to addition and subtraction. 69 3 Multiplication Concept of Multiplication 73 4 Geometric Shapes and Patterns Geometric Shapes 102 Pattern 105 5 Measurement Measurement of length 107 Measurement of weight 111 Measurement of the volume of liquid 114 Measurement of Time 117 6 Currency Bangladeshi currency 121 7 Data Data collection and sorting 125 Contents Chapter Topics Page

2 9 6 7 3 1 8 4 5 20 4 28

1 2024 Elementary Mathematics Let’s count Let’s read (in numbers) Let’s read (in words) Let’s write in words 21 Twenty one Twenty one 22 Twenty two 23 Twenty three 24 Twenty four Chapter One Numbers and Place Values Read numbers and write in words (21 to 100) Let us count the blocks and read the number and write them in words.

2 2024 Elementary Mathematics Let’s count Let’s read (in numbers) Let’s read (in words) Let’s write in words 25 Twenty five 26 Twenty six 27 Twenty seven 28 Twenty eight 29 Twenty nine 30 Thirty

3 2024 Elementary Mathematics Let’s count Let’s read (in numbers) Let’s read (in words) Let’s write in words 31 Thirty one 32 Thirty two 33 Thirty three 34 Thirty four 35 Thirty five 36 Thirty six

4 2024 Elementary Mathematics Let’s count Let’s read (in numbers) Let’s read (in words) Let’s write in words 37 Thirty seven 38 Thirty eight 39 Thirty nine 40 Forty 41 Forty one 42 Forty two

5 2024 Elementary Mathematics Let’s count Let’s read (in numbers) Let’s read (in words) Let’s write in words 43 Forty three 44 Forty four 45 Forty five 46 Forty six 47 Forty seven 48 forty eight

6 2024 Elementary Mathematics Let’s count Let’s read (in numbers) Let’s read (in words) Let’s write in words 49 Forty nine 50 Fifty Read the numbers from 51 to 100 and write them in words. 51 Fifty one 61 Sixty one 71 Seventy one 81 Eighty one 91 Ninety one 52 Fifty two 62 Sixty two 72 Seventy two 82 Eighty two 92 Ninety two 53 Fifty three 63 Sixty three 73 Seventy three 83 Eighty three 93 Ninety three 54 Fifty four 64 Sixty four 74 Seventy four 84 Eighty four 94 Ninety four 55 Fifty five 65 Sixty five 75 Seventy five 85 Eighty five 95 Ninety five 56 Fifty six 66 Sixty six 76 Seventy six 86 Eighty six 96 Ninety six 57 Fifty seven 67 Sixty seven 77 Seventy seven 87 Eighty seven 97 Ninety seven 58 Fifty eight 68 Sixty eight 78 Seventy eight 88 Eighty eight 98 Ninety eight 59 Fifty nine 69 Sixty nine 79 Seventy nine 89 Eighty nine 99 Ninety nine 60 Sixty 70 Seventy 80 Eighty 90 Ninety 100 One hundred

7 2024 Elementary Mathematics 1. Let us read and write the following numbers in words 24, 47, 32, 59, 87, 75, 93, 89, 86, 99, 100 2. Let us write the number of members of 5 joint families in a village numerically in the table below Family-1 Family-2 Family-3 Family-4 Family-5 16 ... ... ... ... 3. Let us count the number of different types of fruit trees in a house and write the numbers in the table below Mango tree Jackfruit Tree Guava tree Coconut tree Blackberry tree Betel nut Tree ... ... ... ... ... ... ... ... ... ... 4. Let us count the number of boys and girls classwise in a school from class one to class five and write in words in the following table. Class Boys Girls One ... ... Two ... ... Three ... ... Four ... ... Five ... ... Let us do

8 2024 Elementary Mathematics Count How many flowers are there in the picture? How can you easily count so many flowers? Do you remember how we formed groups of 10 and counted in the 1st grade? Let us form groups of 10 and count.

9 2024 Elementary Mathematics How many sticks are there in the box below? Let us count using blocks instead of flowers There are 5 blocks of 10 and 4 blocks of 1. The number is fifty-four and we can write 54 in digits. Let us count with blocks instead of sticks.

10 2024 Elementary Mathematics Let us count by creating blocks of 100 and 10. Three blocks of hundred. three hundred Four blocks of tens. Forty Five blocks of each 1 Five Hundred Ten One 3 4 5 The number is three hundred and forty five The number is 345 in digits. Let us write the total number of sticks in numbers: 345 Let us count the number of blocks and write them in numbers hundred ten one The number is: --------------------

11 2024 Elementary Mathematics Let us count the number of blocks and write in numbers. 1. Hundred Ten One The number is: -------------------- 2. Hundred Ten One The number is: -------------------- 3. Hundred Ten One The number is: -------------------- What is the number? how many (hundred) how many (ten) how many (one) 100 10 1 100 10 1 100 10 1 100 10 1 100 10 1 100 Hundred Ten one The number is: -------------------- Let us do

12 2024 Elementary Mathematics 100 10 1 100 10 10 1 100 10 100 100 10 1 100 100 1 10 1 100 10 1 100 10 1 100 10 1 100 100 10 1 100 100 10 10 1 1. Let us count the number of cards of 100, 10 and 1 in the following box. Let us sort the number cards and write in numbers. Let us write the total amount in number = 2. Let us write in numbers: Let us do

13 2024 Elementary Mathematics Let us read the following numbers and write the numbers from 101 to 500 and from 501 to 1000 separately. 112, 898, 304, 505, 712, 925, 134, 198, 1000, 444, 382, 750, 600, 333, 101, 590 Numbers from 101 to 500: Numbers from 101 to 500: Let us read and write in numbers. Read Write in digit (1) One hundred and ten (2) Three hundred and fifty nine (3) Five hundred and eighty five (4) Six hundred and seventy two (5) Eight hundred and fifty (6) Nine hundred and eight

14 2024 Elementary Mathematics Comparison of Numbers Which number is greater between 62 and 45? Let us sort the two numbers in blocks of tens and one 62 45 Let us first compare the blocks of ten. In 62 there are 6 blocks of tens and in 45 there are 4 blocks of tens. Hence,62 is greater.

15 2024 Elementary Mathematics Which number is smaller between 434 and 253? Let us arrange the two numbers in blocks of hundreds, tens and ones. 434 253 Let us first compare the blocks of hundreds. There are 4 blocks of hundreds in 434 and 2 blocks of hundreds in 253. Hence, 253 is smaller.

16 2024 Elementary Mathematics Let us explain which number is larger between 354 and 325. Arrange the two numbers into groups of hundreds, tens and ones. 354 325 Again if the blocks of tens are the same, let us compare the blocks of ones. So the larger number is 354. If the of blocks of hundreds are the same, let us compare the blocks of tens. Since the blocks of hundreds are the same, let us compare the blocks of ten. Between 354 and 325 there are 3 blocks of tens more in 325. Exercise 1. Let us circle the larger number in the box. 85 57 524 348 634 670 423 428 823 540 901 972 2. Let us circle the small number in the box. 75 65 423 337 557 642 876 706 678 948 785 639

17 2024 Elementary Mathematics Let’s count 10 sticks and make a bundle. bundle open stick 1 ten 4 ones Let us write in place value 1 ten and 4 ones How many blocks are there in the picture? 2 tens 3 one 2 tens 3 Let us write in place value 2 tens and 3 ones Place Value How many sticks are there in the picture?

18 2024 Elementary Mathematics How many blocks of hundreds, tens and ones are there in the picture? 3 blocks of hundred = 300 5 blocks of ten= 50 6 blocks of one =6 The number is: 3 hundreds 5 tens and 6 ones. = Three hundred and fifty-six = 356 How many thousands, hundreds, tens and ones are there below? 1000 100 100 1000 100 100 10 10 1 1 10 10 thousand hundred ten one The number is

19 2024 Elementary Mathematics Let’s explain the place value of each digit of 2442. 2 4 4 2 Place value 2 ones 4 tens 4 hundreds 2 thousands 2 4 4 2 2 thousands 4 hundreds 4 tens 2 ones Place value 2 thousands 4 hundreds 4 tens and 2 ones = 2 thousand 4 hundred and 42 2 thousands 4 hundreds 4 tens and 2 ones = 2 thousand 4 hundred and 42 1 2. Let us write the place value from the picture. 3 tens 5 ones ......tens ......... ones place value 30 place value 5 place value ...... place value ...... 2 Let us write the place value in digits and numbers from the picture. .... tens ......ones .... tens ......ones .... tens ......ones the number ....... the number ....... the number .......

20 2024 Elementary Mathematics 3 Let us write the place value of each digit of the numbers 47, 352 and 1000 4 7 7 ones = Place Value 4 tens = 7 40 4 7 Place Value 4 tens = 7 ones = 40 7 Place Value 2 ones= 5 tens= 3 hundreds= 2 50 300 3 5 2 Place Value 3hundreds= 5 tens= 2 ones= 300 50 2 3 5 2 place value 0 one = 0 ten= 0 hundred= 1 thousand= 0 00 000 1000 1 0 0 0 Place Value 1 thousand = 0 hundred = 0 ten = 0 one = 1000 000 00 0 1 0 0 0 1 Fill in the blanks. (1) 56 = 5 tens 6 ones (2) 83 = tens ones (3) 120 = hundreds tens ones (4) 467 = hundreds tens ones (5) 976 = hundreds tens ones (6) 1000 = thousands hundreds tens ones Let us do

21 2024 Elementary Mathematics 2 Let us fill in the blanks. (1) 2 tens 8 ones = 28 (2) 7 tens 4 ones = (3) 1 hundred 8 ones = (4) 2 hundreds 3 tens = (5) 7 hundreds 8 tens 2 ones = (6) 1 thousand = 3. Let us write the place value of each digit of the following numbers. 24, 56, 73, 98, 105, 328, 639, 840, 957, 1000

22 2024 Elementary Mathematics Comparison of Numbers (Using Place Values) Comparison of Two Numbers Which one is larger, 460 or 630? How do we compare? In this case, we will compare the place value of hundreds in two numbers. So 460 is smaller and 630 is larger. Here we will first compare the place values of the digit in hundreds, tens, and ones respectively. Earlier we have learnt to compare numbers using blocks of hundreds or tens. Now, we will compare using place value. In this case, 6 is larger than 4 in the position of hundred. So, 630 is larger than 460. Here the digits in hundreds of the number two are the same (562 and 548). Let us compare the following two numbers 562 and 548 1 Let us compare the following numbers 460 and 630

23 2024 Elementary Mathematics Let us compare the digits in tens. 6 is larger than 4. So 562 is larger and 548 is smaller. So, 562 is larger than 548. Let us do 1. Let’s compare the numbers below. (1) 128, 235 (2) 248, 226 (3) 496, 469 (4) 692, 594 (5) 872, 858 (6) 1000, 998 2. Let us compare the following numbers and sort them in ascending and descending order. Number Ascending order Descending order (1) 430, 428 (2) 678, 675 (3) 827, 948 (4) 985, 950 (5) 744, 722

24 2024 Elementary Mathematics Let us arrange the following numbers in ascending order 232, 223, 239 Let us compare the digits in the hundreds place. The digits in hundreds place are equal. Now let us compare the digits in the tens place. The digits of the tens place of 232 and 239 are the same. The place value of tens in 223 is 2. Therefore 223 is smaller than the other two numbers 232, 239. Now, let us compare 232 and 239. Here 9 is in the ones place of 239. 2 is in the ones place of 232. Since 9 is greater than 2, 239 is the greater number. So, 239 is the largest number. So, 239 is the largest number. Then from smallest to largest: 223, 232, 239. Let us compare the following numbers and arrange them in ascending and descending order. Number Ascending order Descending order (1) 432, 328, 540 (2) 529, 517, 549 (3) 407, 603, 330 (4) 729, 720, 726 (5) 1000, 780, 949

25 2024 Elementary Mathematics Even-odd Numbers and Number Patterns Let us take 2 items at a time and circle them. What is the team called made of 2? I think it can be called a group of 2. Let us take 2 items at a time and circle them in the following picture.

26 2024 Elementary Mathematics Concept of Even and Odd Number picture how much picture how much 2 earrings 1 pair of earrings even 3 earrings 1 pair and 1 earrings odd 2 pigeons 1 pair of pigeons even 4 pigeons 2 pairs of pigeons even 2 coconuts 1 pair of coconuts even 5 coconuts 2 pairs and 1 coconuts odd 2 socks 1 pair of socks even 6 socks 6 socks even 2 blocks 1 pair of blocks even 7 blocks 3 pairs and 1 blocks odd

27 2024 Elementary Mathematics Let us identify even and odd numbers 1 2 3 4 5 6 In this way which other numbers can be formed? I have seen up to 6. Pairs can be formed with 2, 4 and 6. But 1, 3 and 5 cannot be paired. Which other numbers can be formed using like the pairs as above and which numbers cannot be formed? Let us write in the following table. Numbers that form pairs 2, 4, 6, 8, ... ... ... ... ... ... ... Numbers that do not form pairs 1, 3, 5, 7, ... ... ... ... ... ... ... In the table above 2, 4, 6, 8.................. are even numbers and this is the pattern of even numbers and 1, 3, 5, 7 ........... are odd numbers and this is the pattern of odd numbers.

28 2024 Elementary Mathematics Let us identify even and odd numbers from 1 to 50. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 Circled numbers in the table above are the even numbers So, the uncircled numbers will be odd numbers. Even numbers end with 2, 4, 6, 8 or 0. And odd numbers have 1, 3, 5, 7 or 9 at the end. So, what about even and odd numbers?

29 2024 Elementary Mathematics Therefore, we can say, If any number ends with 2, 4, 6, 8 or 0 is an even number or even number pattern. If any number ends with 1, 3, 5, 7 or 9 is an odd number or odd number in pattern. Exercise 1. Let us write even and odd numbers from the following numbers. 8, 13, 20, 11, 24, 9, 18, 7, 21, 16 Even numbers : Odd numbers : 2. Let us write even and odd numbers from the following numbers. 6, 15, 12, 25, 23, 32, 39, 43, 48, 50 Even numbers : Odd numbers : 3. Let us write the even numbers larger than 20 and smaller than 40. 4. Let us write the odd numbers larger than 25 and smaller than 50.

30 2024 Elementary Mathematics What will be the next numbers? Number pattern (1) 2, 4, 6, 8, -, -, - Here, the number pattern is: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, - Here the number pattern is: 15, 20, 25, 30, 35, 40, 45, 50, 55, - Here is the number pattern: 21, 19, 17, 15, 13, 11, 9, _ (2) 15, 20, 25, -, -, - (3) 21, 19, 17, 15, -, -, - Here the difference of two consecutive numbers is always 5. Here the number starts with 15 and increases by 5 in each case. Here the difference of two consecutive numbers is always 2. Here the number pattern is: Here the number starts with 21 and decreases by 2 in each case. Here the difference of two consecutive numbers is always 2. Here the number starts with 2 and increases by 2 in each case. 15, 20, 25, 30, 35, 40, 5 5 5 21 19, 17, 15, 13, 11, 9, 2 2 2 2, 4, 6, 8, 10, 12, 14, 2 2 2

31 2024 Elementary Mathematics (4) What is the pattern of the following numbers? Let us write the next numbers. (5) Let us create a pattern of odd numbers starting with 3 and increasing by 4 in each case. (1) 1, 3, 5, 7, ............... (2) 4, 6, 8, 10, ................ 3, 7, 11, 15, 19, , , , This is an odd number pattern. This is an even number pattern. Here the number starts with 1 and increases by 2 in each case. Here the number starts with 4 and increases by 2 each time. Here the number starts with 3 and let us add 4 in each case. 1, 3, 5, 7, 9, 11, 13, 2 2 2 4, 6, 8, 10, 12, 14, 2 2 2

32 2024 Elementary Mathematics (6) Let us write the next three digits of the following number pattern and explain the rules of the pattern. 0, 5, 10, 15, 20, ..., ..., ... The number pattern is: 0, 5, 10, 15, 20,25,30,35 Then 5 has been added in each case. Here the pattern starts with 0 and increases by 5 in each case. 0, 5, 10, 15, 20, 25, 30, 35, 5 5 5 (7) Let us find the pattern of the following numbers and circle them. (i) From 5 to 10 increasing by 1 (ii) From 48 to 38 decreasing by 2 (iii) From 9 to 24 increasing by 3 (iv) From 50 to 40 decreasing by 5 86 87 9 12 15 18 21 24 45 46 16 18 20 24 65 60 55 50 45 40 36 38 40 42 44 46 48 50 52 54 5 10 48 46 44 42 40 38 20 40 45 50 60 30 35 40 45 50 55 95 10 20 30 5 6 7 8 9 10 12 45 50 12 14 16 18 20 22 80 90 4 25 31 37 40 49 55 10 20 30

33 2024 Elementary Mathematics Exercise 1. What will be the next numbers? (1) 1, 3, 5, 7, -, - , - (2) 2, 3, 5, 8, 12, -, - , - (3) 40, 42, - , 46, - , 50, - 2. Identify the even-odd pattern of the following numbers and write the next numbers. (i) 16, 18, 20, .................. (ii) 37, 39, 41, .................. 3. Create a pattern of odd numbers starting with 47 and decreasing by 2 in each case. 4. Create a pattern of even numbers starting with 24 and increasing by 4 in each case. 5. Write the next three digits of the following number pattern and explain the rules of the pattern (1) 3, 6, 9, ...., ...., ...., (2) 15, 13, 11, ...., ...., ....,

34 2024 Elementary Mathematics Ordinal Number Ordinal Numbers (1st-5th) How can the position of the following animals be expressed? Numbers 1, 2, 3 etc. are used to convey the idea of groups of objects. But ordinal numbers are used to indicate relative positions of objects. Number 1 2 3 4 5 Ordinal Number First Second Third Fourth Fifth I sit on the 2nd position from the left of the 3rd bench from the front. Tuli,where do you sit on the bench in the classroom? Let us find the position of the animals using ordinal number. • Which is the second from the left? ........................................... • Which is the first from the right? ........................................... • Which is the fifth from the right? ........................................... • Which is the fourth from the left ........................................... • Which is the third from the right? ........................................... Now tell, where do you sit on the bench in the classroom? First Second Third Fourth Fifth from the left from the right Fifth Fourth Third Second First

35 2024 Elementary Mathematics Right Right the left the left (1) Circle four students from the left. (2) Circle the fourth person from the left. Let us say the position of each fruit from the left and from the right. Five students are holding their hands. You have to find Ali from the following 5 children. His friend said, Ali is at the second seat. Another friend said, 3 children are seated to his right. 3 2 Four from the left Fourth from the left

36 2024 Elementary Mathematics We can solve this easily by drawing a picture. Front Second from the front 5 more children behind Behind How do you calculate the number of children? How do you calculate the number of children? + = + = Some children are standing in a line. Raju is third from the front and fifth from the back. How many children are there in the line? Tamim is the third youngest and fourth oldest member in his family. How many members are there in the family? Third from the font Fifth from the back Some children are standing in a line. Savita is second from the front and there are 5 more children behind her. How many children are there in the line? 4 Front Behind

37 2024 Elementary Mathematics Ordinal Number (1st-10th) Number 1 2 3 4 5 Ordinal Number First Second Third Fourth Fifth Short Form 1st 2nd 3rd 4th 5th Number 6 7 8 9 10 Ordinal Number Sixth Seventh Eighth Ninth Tenth Short Form 6th 7th 8th 9th 10th Let us say the position of the children using ordinal numbers. • Who is sixth from the front? ................ • Who is seventh from the end? ................ • Who is ninth from the front? ................ • What is the position of Aleya? ................ From the front ................ From the end................ Each child’s position can be expressed in two ways. What is the position of Devid? Behind Front Shanti Raton Aleya Karim Rahim Tamim Devid Sabita Ali Nasima Ten children are standing in a line. Nasima is at the front and Shanti is at the end. Let us say the positions of these children using ordinal numbers.

38 2024 Elementary Mathematics Place seven people from the right in a circle. Place the seventh person from the right in a circle. Remember, seven persons and the seventh person are different. Seven from the right Seventh from the right

39 2024 Elementary Mathematics In a line Shanti is eighth from the back and 5 more students are in front of Shanti. How many students are there in the line? front 5 more from the front 8th from the back behind Number of students: + = In a line Raju is sixth from the front and third from the back. How many children are there? 3

40 2024 Elementary Mathematics Addition (1) Rafi has 43 cards. Tuli has 32 cards. If they put their cards together, how many cards are there in total? 10 10 10 10 3 10 10 10 2 43 cards 32 cards Chapter Two Addition and Subtraction (Without carry) Let us think about how to put them together. If we put the cards together, can the total number of them be more? The mathematical statement is 43 + 32 = How do we write the calculation of the total number of cards in a mathematical statement?

41 2024 Elementary Mathematics Tens Ones The mathematical sentence of the sum of the digits in the ones place is 3+2=5. The mathematical sentence of the sum of the digits in the tens place is 4+ 3 = 7 Tens Ones 4 3 + 3 2 7 5 Addition starts from the ones place. Have you arranged the numbers according to their place value? Have you added the digits in the ones place first? 3 2 + 1 6 4 8 How do we add 32+16?

42 2024 Elementary Mathematics 1. (1) 32 + 30 (2) 51 + 14 (3) 32 + 22 (4) 50 + 20 (5) 65 + 13 Let us add 2 Let us do the following additions. (1) 22 + 36 (2) 72 + 15 (3) 71 + 5 (1) 8 + 60 (5) 35 + 10 • How can we calculate the total number of cards? • The mathematical statement of the calculation is 38 + 24 = Let us arrange the bundles of cards using blocks. Raju has a bundle of 38 colourful cards. Mina has a bundle of 24 colourful cards. How many colourful cards do they have in total?

43 2024 Elementary Mathematics Tens Ones 3 8 + 2 4 3 8 + 2 4 +1 3 8 + 2 4 6 2 38+ 24= 62 Move to the place of tens. Let us arrange the two numbers according to their place values. The mathematical statement of the sum of the two digits in the ones place is 8 + 4 = 12. 12 means 1 ten and 2 ones. Let us write 2 in the ones place and add 1 with the numbers in the tens place. Let us write 3 + 2 + 1 = 6 in the tens place.

44 2024 Elementary Mathematics 1 Let us add. 1 How do we add 23 + 18? 2 38+52= 2 3 + 1 8 1) 23 + 18 6) 37 + 53 9) 65 + 5 7) 45 + 45 10) 42 + 29 8) 47 + 18 2) 45 + 27 3) 52 + 38 4) 78 + 08 5) 26 + 37 How can we do the addition? Is this addition different from others? 3 8 5 2

45 2024 Elementary Mathematics 35 + 6 7 + 36 3 5 + 6 7 + 3 6 2 Let us do the following addition 3 Dilip bought fish for Tk.45 and vegetables for Tk.38 from the market. How much did he spend in total? 4 Mahdi and his friends went to the Probhat ferry on February 21 in two groups. In one group, there are 35 people and in the other group, there are 27 people. How many people were there in total in the two groups? 5 Manha’s family library has 54 storybooks and 38 books on other subjects. In total, how many books are there in the library? 1) 26 + 37 6) 42 + 28 9) 6 + 57 7) 78 + 13 10) 72 + 9 8) 62 + 28 2) 38 + 22 3) 56 + 14 4) 36 + 17 5) 75 + 15 3 How can we do the following addition?