PL BM P2L45 Heuristics Working Backwards WS (1)

Primary 2

Boost! Math

Name HeHureiustriicsst:icWs:oWrkoinrkginBgacBkawckawrdasrd(Lse(sLseosnso4n5)45)
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Primary 3: Boost! Math

Heuristics: Comparison Models
Solve the sums. Show your working clearly.

1. Jerry had some money. He spent $36 on a badminton racket and withdrew
another $90 from the ATM. Now, he has a total of $220. How much money
did he have at first?

Jerry had at first.

2. Keenan had some stamps. He used 6 stamps for postage and bought
another 29 stamps. He now has a total of 57 stamps. How many stamps did
he have at first?

Keenan had stamps at first. 1

Primary 3: Boost! Math

3. Mrs Chia baked some cookies yesterday. Today, she gave 35 cookies to
Macy and baked another 40 cookies. She now has a total of 88 cookies.
How many cookies did she bake yesterday?

Mrs Chia baked cookies yesterday.

4. Lisa had some correction tape refills. She gave 8 of them to Kelsey and
bought another 30 correction tape refills. Now, she has a total of 54
correction tape refills. How many correction tape refills did Lisa have at
first?

Lisa had correction tape refills at first. 2

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5. P2 Honesty was trying to guess the age of their Math teacher, Miss Koh.
Miss Koh said, “First, you divide my age by 3. Next, you add 15 and then
you take away 2. The result is 25.” How old is Miss Koh?

Miss Koh is years old.

6. Half the length of a piece of rope is cut away. Then, Mrs Soh cuts away
another 4 m. The remaining length of rope is 3 m. What is the original length
of the rope?

The original length of the rope was .

3

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7. Jenny’s mother gave her some money that doubled the original amount of
money that Jenny had. Jenny then gave her brother $9. She was left with
$27. How much money did Jenny have at first?

Jenny had at first.

8. A fish seller had some goldfish yesterday. Today, 46 of them died. He bought
another 25 goldfish. Now he has a total of 68 goldfish. How many goldfish
did he have yesterday?

He had goldfish yesterday. 4

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9. Felicia gave away half of her rings and another 6 rings to Gillian. She then
gave away half of the remaining rings to Hillary and was left with 12 rings.
How many rings did Felicia have at the beginning?

Felicia had rings at the beginning.

10. Samuel’s mother had 5 times as much money as him. Her mother spent $60
on a dress. The total amount of their money left was half the amount as
before. How much money did Samuel’s mother have at first?

Samuel's Mother had $ at first.

5

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11. Macy and Nina folded 30 origami cranes in total. Macy gave away 3 origami
cranes and Nina folded another 3 origami cranes. In the end, Macy had two
times as many origami cranes as Nina. How many origami cranes did Macy
fold at first?

Macy folded origami cranes at first

12. Jeanette had 2 times as much money as Sulin at first. After she donated $15
to charity, she had $65 more than Sulin. How much money did Jeanette have
at first?

Jeanette had at first. 6

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13. Alex and Brendan each had a certain amount of money. First, Alex gave
Brendan some money that doubled the amount of money Brendan had.
Then, Brendan gave some money back to Alex that doubled Alex’s
remaining amount of money. In the end, each of them had $36. How much
money did Alex have at first?

Alex had at first.

14. An egg seller sold half of the eggs and another 2 eggs in the morning. He
then sold half of the remaining eggs and another 5 eggs in the afternoon. He
was left with 12 eggs. How many eggs did he have at first?

The egg seller had eggs at first. 7