Math 1A Singapore-Counting and Comparing-Chapter 6.1
Counting and Comparing
Look at the
eggs and count all the eggs.
🥚.🥚.🥚.🥚.🥚
Count all the eggs: 1,2,3,4,5,6,7,8,9,10,11,12,13.
|
🥚.🥚.🥚.🥚.🥚
🥚.🥚.🥚.🥚.🥚
|
10
eggs
|
|
🥚.🥚.🥚
|
3
eggs
|
Count on from 10:
11,12,13.
So, 13 is 10 and 3.
As like as,
11 is 10 and 1.
1. Make a ten
and count.
(a)
🦋.🦋.🦋.🦋
Solution:
Make a ten and count
from 10.
🦋.🦋.🦋.🦋.🦋
Count from 10:
11,12,12,14,15,16.
So, There are 16
butterflies.
16 is 10 and 6.
(b)
🍌.🍌.🍌.🍌.🍌.🍌
Solution:
Make a ten and count extra
bananas.
🍌.🍌.🍌.🍌.🍌
🍌.🍌.🍌
10 and 5 make 15.
15 is 10 and 5.
So, there are 15 bananas.
(c)
🐸.🐸.🐸.🐸.🐸.🐸.🐸.🐸
Solution:
Make a ten and count others.
🐸.🐸.🐸.🐸.🐸
🐸.🐸.🐸.🐸
10 and 8 make 18
18 is 10 and 8.
So, there are 18 frogs.
2. (a) How
many balls are there?
⚽.⚽.⚽.⚽.⚽.
(b) 10 and 5
make 🟦.
(c) 10 + 5 = 🟦.
Solution:
(a)
Make 10 and count the extra balls.
⚽.⚽.⚽.⚽.⚽.
⚽.⚽.⚽.⚽.⚽ à 5
10 and 5 make 15
15 is 10 and 5.
So, there are 15 balls.
(b) 10 and 5 make 15.
(c) 10 + 5 = 15.
3. (a) How
many stamps are there?
🖃.🖃.🖃.🖃.🖃.🖃.🖃.🖃.🖃.🖃
(b) 10 and 4 make
🟦
(c) 10 + 4 = 🟦.
Solution:
(a)
Make a ten and count the extra stamps.
🖃.🖃.🖃.🖃.🖃.🖃.🖃.🖃.🖃.🖃à10
🖃.🖃.🖃.🖃à4
10 and 4 make 14.
So, there are 14 stamps.
(b) 10 and 4 make 14.
(c) 10 + 4 = 14.
4. Complete the addition sentences.
(a)
🐦.🐦.🐦.🐦.🐦.🐦.🐦.🐦.🐦.🐦
10 + 5 = 🟦
(b)
🦆.🦆.🦆.🦆.🦆.🦆.🦆.🦆.🦆.🦆
10 + 🟦 = 🟦
Solution:
(a) 10 + 5 = 15.
(b) 10 + 8 = 18.
5. Count from 1 to 20. Then count backwards.
Solution:
Count from 1 to 20:
1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20.
Count backwards:
20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1.
6. What are the missing numbers?
|
(a)
|
|
17
|
18
|
19
|
|
||
|
(b)
|
9
|
|
|
12
|
13
|
||
|
(c)
|
16
|
|
|
13
|
|
||
|
(d)
|
2
|
4
|
6
|
|
10
|
12
|
|
|
(e)
|
17
|
15
|
13
|
|
|
|
5
|
Solution:
|
(a)
|
16.
|
17.
|
18.
|
19.
|
20.
|
||
|
(b)
|
9.
|
10.
|
11.
|
12.
|
13.
|
||
|
(c)
|
16.
|
15.
|
14.
|
13.
|
12.
|
||
|
(d)
|
2.
|
4.
|
6.
|
8.
|
10.
|
12.
|
14.
|
|
(e)
|
17.
|
15.
|
13.
|
11.
|
9.
|
7.
|
5.
|
7. Which set has the greater number?
|
A
|
B
|
|
🐧.🐧 🐧.🐧.🐧 |
🐧.🐧.🐧 🐧.🐧.🐧 🐧.🐧 |
|
Answer: B
|
|
8. Which set has the smaller number?
|
A
|
B
|
|
🦋.🦋 🦋.🦋 |
🦋.🦋.🦋 🦋.🦋.🦋 🦋.🦋 |
|
Answer: A
|
|
9. Which set has the greatest number?
Which set has the smallest number?
|
A
|
B
|
|
🍍.🍍 🍍.🍍 🍍.🍍 |
🍍.🍍 🍍.🍍 🍍.🍍 🍍.🍍 🍍.🍍 |
|
C
|
D
|
|
🍍.🍍 🍍 🍍.🍍 |
🍍 🍍.🍍 🍍.🍍 🍍.🍍 |
Solution:
Count the pineapples of each set. And we get:
|
A
|
B
|
|
6
|
10
|
|
C
|
D
|
|
5
|
7
|
So, Set B has the greatest number
and set C has the smallest number?
10. (a) Which is greater, 14 or 17?
(b) Which is
smaller, 19 or 12?
Solution:
(a)
●.●.●.●.●.●.●.●.●.●à 10
●.●.●.●.●.●.●.●.●.●à 10
14 = 10 + 4
17 = 10 + 7
7 > 4
So, 17 is greater than 14.
(b)
●.●.●.●.●.●.●.●.●.●à 10
●.●.●.●.●.●.●.●.●.●à 10
19 = 10 + 9
12 = 10 + 2
2 < 9
So, 12 is smaller than 19.
11. Compare these numbers:
|
12
|
16
|
20
|
8
|
(a) Which number is greatest?
(b) Which number is the smallest?
(c) Arrange the numbers in order. Begin with the smallest.
Solution:
(a) 20 is the greatest number.
(b) 8 is the greatest number.
(c) Arranged numbers as below:
|
8
|
12
|
16
|
20
|