How To Do Multiplications With Decimals

It always seems difficult to solve long multiplication questions, especially if the decimal numbers are involved.

Here is a simple way of finding the answer of long multiplications with decimal points or number with zeros at the end:

1. Ignore all the zeros at the end of numbers and decimal points

2. Do the simple multiplication

3. Add all the zeros at the end of the answer

4. Count all the digits after the decimal points and place the decimal point.

Example 1:

5 x 450 =

1. Ignore the zeros: 5 x 45 = 225

2. Add all the zeros at the end of the answer: 2250

5 x 450 = 2250

Example 2:

20 x 350 =

1. Ignore the zeros: 2 x 35 = 70

2. Add all the zeros at the end of the answer: 7000

20 x 350 = 7000

Example 3:

3.4 x 250

1. Ignore all the zeros at the end of numbers and decimal points:

2. Do the simple multiplication: 34 x 25 = 850

3. Add all the zeros at the end of the answer: (250 - >1 zero) 8500

4. Count all the digits after the decimal points and place the decimal point (1 digit for 3.4): 850.0

3.4 * 250 = 850.0 = 850

Example 4:

2.5 x 35.23

1. Ignore all the zeros at the end of numbers and decimal points: 25 x 3523

2. Do the simple multiplication: 25 x 3523 = 88075

3. Add all the zeros at the end of the answer: No zeros at the end of numbers

4. Count all the digits after the decimal points and place the decimal point ( 1 digit for 2.5 and 2 digits for 35.23 = 3 digits after the decimal point in total)

25 x 3523 = 88.075