Back to Unit 5

How to divide decimals – Short Division

Labels in a division problem                                                             Quotient

Divisor                                 Dividend

If there is no decimal point in the divisor:

Step#1 – Bring up the decimal point directly above where it is in the dividend.

Step #2 – Divide using short division.

1. 6

5 8.30

Carry the leftover to the 0

Divide 8 by 5, put the 1 directly above the 8.  1 times 5 is 5. 8 - 5 = 3, carry the 3 on the bottom making 30.  30 divided by 5 is 6, place the 6 directly above the 0.

If there is a decimal point in the divisor:

Step#1 – Bring up the decimal point directly above where it is in the dividend.

.

.         .

Step #2 – Divide using short division.

1  6 0.

.05. 8.300.

Carry the leftover to the 0

Divide 8 by 5, put the 1 directly above the 8.  1 times 5 is 5. 8 - 5 = 3, carry the 3 on the bottom making 30.  30 divided by 5 is 6, place the 6 directly above the 0. Next 0 divided by 5 is 0.

Using mental math to divide by powers of 10

Move the decimal point to the left the number of zeros in the divisor.  Then divide by the whole number.  See examples below:

A)        320,0 00 ¸ 8 00 =

3,200 ¸ 8 = 400

B)  5,400,000 ¸ 9 X 104 =

540 ¸ 9 = 60

C)    72.543 ¸ 100 = .72543

Remember if you are multiplying by a positive power of 10 the number gets bigger so you move the decimal point to the right.

Use Mental Math to solve the following problems:

1)  360,000 ¸ 600 =                                      2)  .234 ¸ 100 =

3)  98.33 x 1,000 =                                       4)  36,000 ¸ 9,000 =

5)  4.213 ¸ 100 =                                          6)  8.75 x 105 =