DIVISION 5.NBT.2
Dividing Whole Numbers and Decimals by Powers of Ten
Purpose:
To illustrate the placement of decimal points when dividing by powers of 10
Materials:
Blank Decimal Squares - Dividing by Powers of 10 (attached)
TEACHER MODELING/STUDENT COMMUNICATION
1. Distribute Blank Decimal Squares "Dividing by Powers of 10" to students.
Activity
Sheet
pencils
or colored
markers
a. Shade the top blank square in #1a on your sheet for .80 and the lower square to show
.80 ÷ 10. Complete the equation for this quotient. (.80 ÷ 10 = .08) Discuss that the square
for .80 has 80 shaded parts and 80 ÷ 10 = 8 shaded parts. Since there are 100 equal parts in
a whole square, the decimal for 8 shaded parts out of 100 is .08.
b, c. Similarly, shade the top square in #1b and #1c on your sheet for 1.0 and 1.2. Then shade the
lower squares for the quotients and complete the equations. (1.0 ÷ 10 = .1 and 1.2 ÷ 10 = .12)
Discuss that these two quotients can be found by dividing whole numbers of shaded parts by 10.
That is in #1b, 10 shaded parts can be divided by 10, and in #1c each of the12 shaded columns
of the top square can be divided by 10 to obtain .01, or the tenths squares for 1.2 can be replaced
by hundredths squares for 1.20 and then 120 parts can be divided by 10 to obtain .12.
1a.
b.
÷ 10
.80 ÷ 10 = .08
c.
÷ 10
1.0 ÷ 10 = .10
÷ 10
1.2 ÷ 10 = .12
d. What patterns do you see in computing these quotients? (The decimal point in the number
being divided by 10 is moved one place to the left; and if the number being divided is a whole
number, give it a decimal point and move the point one place to the left.)
2a. Shade the top square in #2a on your sheet for 1.0 and the lower square to show
1.0 ÷ 100. Complete the equation for this quotient. (1.0 ÷ 100 = .01) Discuss that the
square for 1.0 has 100 shaded parts and 100 ÷ 100 = 1 shaded part. Since there are
100 parts in a whole square, the decimal for 1 shaded part out of 100 is .01.
÷ 100
1.0 ÷ 100 = .01
b. Similarly, shade the top two squares in #2b to represent 2.0. Then shade the lower
square for the quotient and complete the equations. (2.0 ÷ 100 = .02) Discuss that
this quotient can be found by dividing whole numbers of shaded parts by 100. That
is, 200 shaded parts from the two whole squares divided by 100 equals 2 shaded
parts out of 100and the decimal for this amount is .02.
c. What patterns do you see in computing these quotients? (The decimal point in the number
being divided by 100 is moved two places to the left; and if the number being divided is a
whole number, give it a decimal point and move the point two places to the left.)
3a. Shade the first square in #3a for 1.0 (one whole square) and the second square to show
1.0 ÷ 1000. Complete the equation for this quotient. (1.0 ÷ 1000 = .001) Discuss that the
square for 1.0 has 1000 shaded parts and 1000 ÷ 1000 = 1 shaded part. Since there are 1000
equal parts in a whole square, the decimal for 1 shaded part out of 1000 is .001.
÷ 1000
1.0 ÷ 1000 = .001
b. Repeat this activity for 3b on your sheet to illustrate 2 ÷ 1000 and complete the equation.
Remind students that to divide 2.0 by 1000, they can divide each whole square separately.
c. What patterns do you see in computing these quotients? (The decimal point in the number
being divided by 1000 is moved three places to the left; and if the number being divided is a
whole number, give it a decimal point and move the point three places to the left.)
3
4. Why is 1000 called the "third power of 10?" (1000 = 10 ) Why is 100 called the "second
2
1
power of 10?" (100 = 10 ) Why is 10 called the "first power of 10?" (10 = 10 )
5. What patterns can you see when numbers are divided by powers of 10? (If the number is a
decimal, the decimal point is moved to the left, and the number of places it is moved is the
power of 10. When dividing a whole number by a power of 10, give it a decimal point and the
number of places the decimal is moved to the left is also the power of 10.)
INDEPENDENT PRACTICE and ASSESSMENT
Worksheet 5.NBT.2 #2