ESTIMATING DECIMALS MULTIPLICATION WORKSHEET

Problem 1 :

Estimate the product :

28.3 x 3.2

Problem 2 :

Estimate the product :

34.3 x 3.5

Problem 3 : 

Estimate the product :

74.8 x 5.7

Problem 4 :

Estimate the product : 

328 x 42

Problem 5 :

Estimate the product :

428.5 x 57.3

Problem 6 :

Estimate the product :

5283 x 78

Problem 7 :

Estimate the product :

6523.56 x 73.569

Problem 8 :

Estimate the product :

806.67 x 68.69

Detailed Answer Key

Problem 1 :

Estimate the product :

28.3 x 3.2

Solution : 

In the above product, the numbers can be rounded as given below.

28.3  -----> 30

3.2 -----> 3

Now, the above product will become (30 x 3).

Then, 

=  3 x 3  =  9 -----> 90

So, the estimated product is 90.

Problem 2 :

Estimate the product :

34.3 x 3.5

Solution :

In the above product, the numbers can be rounded as given below.

34.3  -----> 30

3.5 -----> 4

Now, the above product will become (30 x 4).

Then, 

=  3 x 4  =  12 -----> 120

So, the estimated product is 120.

Problem 3 :

Estimate the product :

74.8 x 5.7

Solution :

In the above product, the numbers can be rounded as given below.

74.8  -----> 70

5.7 -----> 6

Now, the above product will become (70 x 6).

Then, 

=  7 x 6  =  42 -----> 420

So, the estimated product is 420.

Problem 4 :

Estimate the product : 

328 x 42

Solution :

This is bit different case.

In the above product, the numbers can be rounded as given below.

328  -----> 300

42 -----> 40

But both the numbers are decreased. (Because 328 is close to 300 and 42 is close to 40)

Now, the estimated product ===> 300 x 40 = 12000

But the exact product is 13776.

Here, there is bit higher difference between the exact product and estimation.

So, we can round the given numbers as given below.

328 -----> 350

42 -----> 40

Now, the product will become 350 x 40

Then,

=  35 x 4  =  140 -----> 14000

So, the estimated product is 14000.

Problem 5 :

Estimate the product :

428.5 x 57.3

Solution :

In the above product, the numbers can be rounded as given below.

428.5  -----> 400

57.3 -----> 60

Now, the above product will become (400 x 60).

Then

=  4 x 6  =  24 -----> 24000

So, the estimated product is 24000.

Problem 6 :

Estimate the product :

5283 x 78

Solution :

In the above product, the numbers can be rounded as given below.

5283  -----> 5000

78 -----> 80

Now, the above product will become (5000 x 80).

Then

=  5 x 8  =  40 -----> 400,000

So, the estimated product is 400,000.

Problem 7 :

Estimate the product :

6523.56 x 73.569

Solution :

In the above product, the numbers can be rounded as given below.

6523.56  -----> 7000

73.569 -----> 70

Now, the above product will become (7000 x 70).

Then, 

=  7 x 7  =  49 -----> 490,000

So, the estimated product is 490,000.

Problem 8 :

Estimate the product :

806.67 x 68.69

Solution :

In the above product, the numbers can be rounded as given below.

806.67 -----> 800

68.569 -----> 70

Now, the above product will become (800 x 70).

Then, 

=  8 x 7  =  56 -----> 56,000

So, the estimated product is 56,000.

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