Grade 4 - Progress in Mathematics

Multiply Four-Digit Numbers

4-9

Mr. Carter built houses on 6

neighboring plots of land. Each

plot is 6,875 square feet. On

how many square feet of land

did he build the houses?

To find how many square feet,

multiply: 6 
 6875

First, estimate using

front-end digits:

Then multiply.

5 4 3

6 8 7 5


 6

4 1 , 2 5 0

Mr. Carter built the houses on 41,250 square feet of land.

Study these examples.

1 2 3 1

1 4 0 6 $ 2 5. 2 0


 4 
 7

5 6 2 4 $ 1 7 6. 4 0

6875


 6

about 36 ,000

Think

6875 6000, so the answer is

greater than 36,000.

Think

41,250 is greater than 36,000.

The answer is reasonable.

Use front-end digits to estimate. Then multiply.

Use mental math when you can.

1. 2221 2. 1022 3. 2432 4. 3123
   
   3
   4
   2
   3


2. 1035 6. 2164 7. 1146 8. 3257
   
   7
   4
   6
   3
   3.2

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