Question

Explain how to multiply decimals.

Answer 1

Multiplication of decimals is done in same manner as you multiply normal numbers. Only thing to be learnt is to how to put decimal point after the multiplication is carried out.
Let us take some examples.
2.31 $\times$ 1.2
Multiply in a normal manner, as if there is no decimal.
231 $\times$ 12 = 2772.
Now add the places after decimal in both the numbers.
In 2.31 there are 2 places after decimal and in 1.2 there is 1 place after the decimal.
Hence, totally there are 3 places after the decimal.
Now in the product 2772, start from right and count 3 places to the left and put the decimal point.
$\to$ 2 . 7 7 2
So 2. 31 $\times$ 1.2 = 2.772
b) 3.023 $\times$ 0.033
3023 $\times$ 33 = 99759.
No of places on right hand side number after the decimal (i.e. 3.023) = 3.
No of places on left hand side number after the decimal (i.e.0.033) = 3.
So we have totally 6 places.
Now take the number 99759. Counting 6 places from right, it is not possible since there are only 5 places.
So add a 0 on the left side of the number without changing its value.
So 99759 becomes 099759.
Now count 6 places from right and put the decimal $\to$.099759.
If there is no number before the decimal place, we must put 0 before the decimal place. Hence, this will become 0.099759.
Hence, 3.023 $\times$ 0.033 = 0.099759