Grade 4 - Progress in Mathematics

Multiply with Regrouping

4-6

Cody needs 102 pushpins. There are

35 pushpins in each packet. Will Cody

have enough if he buys 3 packets?

To find whether Cody will have

enough pushpins,

find the product: 3
 35

First, estimate using

front-end digits: 3 
 35

3 
 30  90

Then, multiply.

1

3 5


 3

5

105  102

1

3 5


 3

1 0 5

Multiply the ones.

Regroup.

Multiply the tens.

Add the regrouped tens.

3 
5 ones15 ones

15 ones 1 ten 5 ones

3 
3 tens9 tens

9 tens1 ten 10 tens

Multiply.

1. 18 2. 16 3. 38 4. 24 5. 16 6. 25
   
   3
   5
   2
   3
   4
   2


2. 15 8. 29 9. 44 10. 32 11. 22 12. 58
   
   7
   3
   8
   6
   7
   5

Think

The actual product

will be greater than 90.

Cody will have enough pushpins.

3.2

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