Math Activity
6.2
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6.25
MATH ACTIVITY 6.2
Decimal Operations with Decimal Squares
Virtual
Manipulatives
www.mhhe.com/bbn
Purpose: Use Decimal Squares to model the four basic operations on decimals.
Materials: Copies of Blank Decimal Squares from the website and Decimal Squares in the
Manipulative Kit or Virtual Manipulatives.
1. The concept of addition of whole numbers, that is,
putting together or combining amounts, is the same
for addition of decimals. If the shaded amounts of
Decimal Squares for .2 and .8 are combined, the total
equals one whole square. Use your deck of Decimal
Squares and answer parts a, b, and c. Write an addition equation for each pair of decimals.
*a. Find three pairs of Decimal Squares for tenths
(red squares) for which the sum of the decimals
in each pair is 1.0.
.2 + .8 = 1.0
b. Find three pairs of Decimal Squares for hundredths (green squares) for which the sum
of the decimals in each pair is 1.0. Use decimals not equivalent to those used in part a.
c. Find three pairs of Decimal Squares for thousandths (yellow squares) for which
the sum of the decimals in each pair is 1.0. Use decimals not equivalent to those
used in parts a and b.
2. The comparison concept for determining the difference of two whole numbers can
also be used to find the difference of two decimals. By lining up the Decimal Squares
for .65 and .4, as shown at the left, the shaded amounts can be compared to show the
difference is .25. Find pairs of Decimal Squares from your deck that satisfy the following conditions and write a subtraction equation for each pair of decimals.
a. Two red Decimal Squares whose decimals have the greatest difference and two red
Decimal Squares whose decimals have the smallest difference.
b. Two green Decimal Squares whose decimals have the
greatest difference and two green Decimal Squares
whose decimals have the smallest difference.
.65 − .4 = .25
c. A red Decimal Square and a green Decimal Square
whose decimals have the greatest difference.
3. The product 6 × .14 is illustrated here by using repeated
addition and shading a blank hundredths square. Use
Blank Decimal Squares and different colors of shading to
illustrate each of the following products. Write a multiplication equation for each pair of decimals.
*a. 5 .05
b. 4 .47
c. 3 .650
6 × .14 = .84
d. 10 .08
4. The quotient .45 3 is illustrated at the left by shading a Blank Decimal Square for
.45 and using the sharing concept of division to divide the shaded amount into 3 equal
parts. Use Blank Decimal Squares to illustrate each of the following quotients. Write
a division equation for each pair of decimals.
.45 ÷ 3 = .15
ben19456_ch06.indd 363
a. .8 4
b. .50 10
c. .400 5
d. .60 15
12/1/08 4:29:52 PM