Exercise 3.2 (Patterns in numbers)

Exercise 3.2

1. Circle/underline the multiples of 9 (by using casting out nine).

a) 9443

b) 1008

c) 24689

d) 23769

e) 13476

a) 9443

9443

4+4+3 = 11

= 1 + 1 = 2

2 ≠ 9

Not multiple of 9

b) 1008

1+8=9

Multiple of 9

c) 24689

24689

2+4+6+8 = 20

= 2 + 0

2≠9

Not multiple of 9

d) 23769

23769

It is multiple of 9

e) 13476

13476

 1+4+7 = 12

1+2 = 3 ≠ 9

It is not multiple of 9

2. Circle the correct addition fact (by using casting out nine method).

a) 4355 + 5369 = 9724

b) 7632 + 2213 = 9845

c) 6023 + 3203 = 9220

d) 2436 + 5315 = 7701

a) 4355 + 5369 = 9724

4355 + 5369 = 9724

3+5+5 = 4

13 = 4

1 + 3 = 4

4 = 4

It is correct addition fact.

b) 7632 + 2213 = 9845

7632 + 2213 = 9845

 2+2+1+3 = 8

8 = 8

It is correct addition fact.

c) 6023 + 3203 = 9220

6023 + 3203 = 9220

 2+3+2+3 = 2+2

2 + 8 = 4

10 = 4

1 ≠ 4

It is not correct addition fact.

d) 2436 + 5315 = 7701

2436 + 5315 = 7701

2+4 + 5+3+1+5 = 7 + 7 + 1

6+14  = 15

20 = 15

2 ≠ 6

It is not correct addition fact.

3. Circle the correct subtraction fact (by using casting out nine methods).

a) 7420 − 3625 = 3795

b) 2362 − 632 = 1720

c) 6732 − 4361 = 2371

d) 3264 − 1063 = 2200

a) 7420 − 3625 = 3795

7420 − 3625 = 3795

7 + 4 + 2 − 7 = 3+7+5

13 – 7 = 15

6 = 6

It is correct subtraction fact.

b) 2362 − 632 = 1720

2362 − 632 = 1720

4 − 2 = 1

2 = 1

2 ≠ 1

It is not correct subtraction fact.

c) 6732 – 4361 = 2371

6732 – 4361 = 2371

6+3 – 4+1 = 3+1

9 − 5 = 4

4 = 4

It is correct subtraction fact.

d) 3264 − 1063 = 2200

3264 − 1063 = 2200

2 + 4 − 1 = 2 + 2

6 – 1 = 4

5 ≠ 4

It is not correct subtraction fact.