Math 1A Workbook Exercise 21-24 Singapore Part 5
1A Workbook Exercise 21-24
Exercise 21
1. Fill in the blanks.
(a) There are 6 children. 4 of them are boys. There are ___ girls.
(b) There are 6 fish altogether. There are 2 big fish. There are
___ small fish.
(c) There are 8 fruits. 5 of them are apples. There are ___ pears.
Answer:
(a) 2
(b) 4
(c) 3
2. Fill in the blanks.
(a) There are 8 trees altogether. 4 of them are cut down. ___
trees are left.
(b) I bought 7 oranges. I ate 2 of them. ___ oranges are left.
(c) There are 6 fruits altogether. 2 of them are papayas. The rest
are pineapples. There are ___ pineapples.
(d) There are 5 children. 3 of them are swimming. ___ are not
swimming.
Answer:
(a) 4
(b) 5
(c) 4
(d) 2
Exercise 22
1. Look at the picture and complete the number sentence.
(a) 6 – 2 = 4
(b) 6 – 2 = 4
(c) 4 – 1 = 3
(d) 7 – 2 = 5
2. Tell two different stories for each picture (a and b).
Then complete the number sentences.
(a)
Story 1: There
are 6 people in a park. 4 of them are elder. 2 of them are children.
Number Sentence 1: 6 – 4 =
2
Story 2: There
are 6 people in a park. 1 of them is reading a book. 5 of them are not reading
books.
Number Sentence: 6 – 1 =
5
(b)
Story 1: There
are 7 rabbits. There are 6 black rabbits. There are 1 white rabbit.
Number Sentence 1: 7 – 6 =
1
Story 2: There
are 7 rabbits. 3 of them run away. 4 of them are not run away.
Number Sentence 2: 7 – 3 =
4
3. Write 2 subtraction sentences for each picture.
|
(a)
|
🍏. 🍏. 🍏. 🍏.
|
🍏. 🍏.
|
|
(b)
|
🌽. 🌽. 🌽
|
🌽. 🌽. 🌽. 🌽.
|
|
(c)
|
🍄. 🍄
|
🍄. 🍄.🍄
|
|
(d)
|
🥭. 🥭. 🥭. 🥭. 🥭
|
🥭. 🥭. 🥭
|
Solution:
(a)
6 – 4 = 2.
6 – 2 = 4.
(b)
7 – 3 = 4.
7 – 4 = 3.
(c)
5 – 2 = 3.
5 – 3 = 2.
(d)
8 – 5 = 3.
8 – 3 = 5.
Exercise 23
1. Fill in the missing numbers.
(a)
5 – 2 = ⬜
↗⬜
(b)
4 – 1 = ⬜
↗⬜
(c)
6 – 6 = ⬜
↗⬜
(d)
9 – 7 = ⬜
↗⬜
Solution:
(a)
5 – 2 = 3
↗ 2
(b)
4 – 1 = 3
↗ 1
(c)
6 – 6 = 0
↗ 6
(d)
9 – 7 = 2
↗ 7
2. Subtract
8 – 4 = ?
7- 4 = ?
10 - 4 = ?
6 – 3 = ?
9 – 2 = ?
8 – 2 = ?
Solution:
8 – 4 = 4.
7- 4 = 3.
10 - 4 = 6.
6 – 3 = 3.
9 – 2 = 7.
8 – 2 = 6.
Exercise 24
1. There are 7 bats in a box. Take away 2 bats.
There will be ___ bats left.
Solution:
7 – 2 = 5.
There will be 5 bats left.
2. I have 6 bottles of milk. I give away 4
bottles. There are ___ bottles left.
Solution:
6 – 4 = 2.
There are 2 bottles left.
3. There are 8 hats. 3 are big hats. The rest are
small hats. There are ___ small hats.
Solution:
8 – 3 = 5.
There are 5 small hats.
4. I buy 10 cup cakes. I put 4 of them on a plate.
The rest are in the box. There are ____ cup cakes in the box.
Solution:
10 – 4 = 6.
There are 6 cup cakes in the box.