# Decimals Review Lesson

This is a free lesson with varied exercises and many word problems for reviewing decimal topics for 4th grade (add, subtract, multiply, compare). It uses decimals with up to 2 decimal digits.

1. Draw pictures to represent the decimals.

 a.  1.3 b.  0.8 c.  2.7

2. Write the decimals as fractions.

 a.  2.7 b.  0.02 c.  0.29 d.  1.35

3. Make a number line...

a. from 3.4 till 5.4, with tick marks at every tenth.

b.  from 0.38 till 0.54, with tick marks at every hundredth.

4. In a., find what was subtracted. In b., figure out the operation done in each step.

a.
 – – – – – – – – 7.76

7.6

7.4

7.33 7.2 7.14 7.1 7 6.5
b.        1.8

2

2.45

2.13 2.1 2.67 2.5 2.62 3

5. Continue the patterns.

 a. 8 × 0.01 = ______ 8 × 0.02 = ______ 8 × 0.03 =  ______ 8 × 0.04 = ______ b. 10 × 1.2 = ______9 × 1.2 = ______ 8 × 1.2 =  ______ 7 × 1.2 = ______ c. 1 × 0.1 = ______2 × 0.2 = ______ 3 × 0.3 =  ______ 4 × 0.4 = ______ d. 4 × 0.5 = ______4 × 1.5 = ______ 4 × 2.5 =  ______ 4 × 3.5 = ______

6. Multiply in columns. Estimate first!

 a.  7 × 6.2 b.  8 × 9.45 c.  11 × 3.2 d.  24 × 13.97 Estimation: Estimation: Estimation: Estimation:    7. Find the missing factor.

 a.  3 × _____ = 0.09 b.  3 × _____ = 0.9 c.  3 × _____ = 0.21 d.  _____ × 0.7 = 6.3 e.  7 × _____ = 0.49 f.  11 × _____ = 0.66 g.  10 × _____ = 0.5 h.  10 × _____ = 4.0 i.  _____ × 0.11 = 1.21 j.  ____ × 1.05 = 5.25 k.  8 × _____ = 4.8 l.  _____ × 2.3 = 9.2

8. Add or subtract in columns. Estimate first!

 a.  34.56 + 198.04 b. 15.09 – 3.46 c.  15.2 – 9.99 Estimation: Estimation: Estimation:   d.  1.5 + 4.67 + 8.92 e.  2.034.56 + 34.5 + 98.73 Estimation: Estimation:  9. Add mentally. Pay close attention to the number that only has tenths. Before adding, tag a zero to it
so the addends will have the same amount of decimals.

 a.  0.40  +  0.07 = _______ b.  0.05  +  0.8  = _______ c.  0.9  +  0.04  = _______ d.  0.21  +  0.5  = _______ e.  0.37  +  0.3  = _______ f.  0.6  +  0.19  = _______

10. Compare and write  < , > , or  =  in the boxes.

 a. 0.23 0.2 e. 0.35 0.39 i. 6.5 6 1 2
 b. 1 2 0.7 f. 5.6 5.45 j. 7.8 8.7
 c. 1.23 1 1 2 g. 0.9 0.09 k. 7.78 7.7
 d. 1.38 1.8 h. 14 10 1.3 l. 0.8 0.18

11. Write the decimals in order from smallest to greatest:  5.6   5.06   5.56   5.62   6.5   5.0  5.16

12. Solve the word problems.

a.  Dad bought ice cream for the whole family - dad, mom, and four kids.
The basic price was \$1.25 for one scoop and an extra scoop cost
\$0.60. Dad and two of the kids got an extra scoop. What was the total bill?

b.  Dad paid with \$10. What was his change?

c.  Debbie earns \$0.42 each time she sells a magazine
on her website. If she sells 20 magazines a day, will
she earn \$30 (or more) in a week?

d.  Here is how many magazines Debbie actually sold during one week:

 Monday Tuesday Wednesday Thursday Friday Saturday Sunday 16 17 21 15 17 13 10

How much money did she make by selling the magazines?

 e.  The earth goes around the sun one time in 365.24 days.      This is called the solar year.       It is also 365 days, 5 hours, and 48 minutes.       Use the decimal 365.24 days per year.       How many days are in two solar years?         And in four solar years?        * In how many solar years does the additional 0.24 days         over the 365 days make an extra day?        * Do you know when that day is, and what the year with the extra day is called? f.  The time between two new moons is 29.531 days.      This time period is called a lunar month.      How many days are in 12 lunar months? g.  Mercury goes once around the sun in 87.96 of our days.  That is one Mercurial year.     First, round this number to the nearest ten.      Then use the rounded number, and estimate how many Mercurial years      it takes to make approximately ONE of our years. (Our year is 365 days).        Lastly, calculate exactly how many our days there      are in such an amount of mercurial years.

This lesson is taken from Maria Miller's book Math Mammoth Decimals 1, and posted at www.HomeschoolMath.net with permission from the author. Copyright © Maria Miller.

#### Math Mammoth Decimals 1

A self-teaching worktext for 4th grade that gives a solid foundation for decimals. It covers tenths and hundredths, comparing decimals, adding and subtracting decimals both mentally and in columns, multiplying decimals by whole numbers, rounding, estimating, and money problems.