Multiplying and Dividing Decimals by Powers of Ten

Sidewalk Chalk Decimal Fun

 First the girls wrote a giant decimal number with sidewalk chalk.

Then they stood on the decimal in the origional number, but then moved to where the decimal would move when told to multiply by a power of ten like 100, 1000, etc. or to divide by a power of ten.

We used the following chant with actions to help in remembering which way to move the decimal when multiplying or dividing by a power of ten in exponent form. The number of zeros in the number you are multiplying by (like 100 or 10,000) is the same as the number of the exponent.

Move the Decimal

(Snap to the beat)

To MULTIPLY a number by a power of ten

Move the decimal to the RIGHT (jump)

Move the decimal to the RIGHT (jump)

You move as many places as the number of the power

And jump to the RIGHT (jump)

Jump to the RIGHT (jump).

To DIVIDE a number by a power of ten

Move the decimal to the LEFT (jump)

Move the decimal to the LEFT (jump)

You move as many places as the number of the power

And jump to the LEFT (jump)

Jump to the LEFT (jump).

Edible Decimal Dice Activity

Shake 3 or 4 dice and write each number as a digit in a 3-or 4-digit decimal number. Then place a chocolate chip where you want the decimal to be. Make a dice or spinner with different powers of ten. Shake the dice or spin the spinner to see what power of ten you will multiply your decimal by. Then move the decimal to the correct spot to show what the product is. Write in extra zeros if needed so your decimal is in the right place.