24
Multiplying and Dividing Whole Numbers
and Decimals
To multiply whole numbers and decimals, place the numbers, called the factors, in pairs in a vertical
list. Starting with the right-hand number on the bottom, fi nd the partial products and add them. To fi nd
the number of decimal places needed in the fi nal product, add the number of places in each number
(two decimal places plus three decimal places means the product must have fi ve decimal places).
Skills Workshop 8
To divide whole numbers and decimals, place the dividend under the division symbol and the divisor
to the left of the division symbol. The answer, called the quotient, is placed above the division symbol. To
solve the equation, work from the left of the dividend and estimate how many times the divisor goes
into the fi rst number or group of numbers. Carry the remainder down along with the next number and
repeat the process. Do this until the fi nal quotient is found. When dividing decimals, move the decimal
point in the divisor until it is a whole number. Then, move the decimal point in the dividend the same
number of places. The decimal point in the quotient should be above this moved decimal point.
See It
Find the product of 81.6 times 3.5.
Step 1: Place 81.6 over 3.5 in a vertical list and count the total number of
decimal places (2).
Step 2: Multiply 816 by 5 (816 × 5 = 4,080).
Step 3: Multiply 816 by 30 (816 × 30 = 24,480).
Step 4: Add the partial products and count off two decimal places (285.60 or
285.6).
Check It
1. 1,024 × 4.5 =
2. 86.7 ÷ 3 =
3. 4,327 × 209 =
4. 945.35 ÷ 36.5 =
437.05
× 2.5
218525
874100
1092625
1,092.625
Two decimal places
One decimal place
Product of 43705 times 5
Product of 43705 times 20
Sum of the partial products
Count off three decimal places to
find the final product
437.05 × 2.5 = 128.48 ÷ 5.5 =
)1284.8
55
23.36
110
184
Product of 2 times 55
Bring 4 down
165
Product of 3 times 55
198
Bring 8 down
0
165
Product of 3 times 55
330
Add a 0 to the dividend and bring it down
330
Product of 6 times 55
0
No remainder
Move the decimal point one place to the right
in both the divisor and the dividend to make
the divisor a whole number