How many decimal places are in the product of a number with decimal places to the hundredths multiplied by a number with decimal places to the tenths?

Answer 1

Three decimal places.

A simple rule of thumb for multiplying decimals; ignore the decimals and just multiply the number together.

0.111 x 0.1; would become 111 x 1 = 111

Then count all the numbers after the decimal. 0.111 (3) and 0.1 (1) 3+1=4

And put the decimal point that many places from the right.

With four places 111 becomes:

11.1 ( one place)

1.11 (two places)

0.111 (three places)

0.0111 (four places)

0.111 x 0.1 = 0.0111

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There is 2 decimals digits in hundredths and 1 decimal digit in tenths, thus when multiplied together they will have 2 + 1 = 3 decimal digits.

However, if the decimal digits on the right hand end are zero they are not written, and less than 3 can be written.

Examples:

0.97 × 0.3 = 0.291

0.17 × 0.3 = 0.051

0.12 × 0.5 = 0.060 = 0.06
When multiplying decimal numbers, multiply them without the decimal point and then put the decimal point back in to the result by counting the total number of digits after the decimal points in the original numbers and ensuring that the same number are in the result.

Thus as the first number has 2 decimal places and the second that 1 decimal place, the result will have 1 + 2 = 3 decimal places.