Download SWilliams Carr Lesson 7 Practice Set C

Round decimals using a number line,
Practice Set C
Name:
Date:
1. Luke thinks that the moon Janus - .69466, rounded to the nearest hundredth is
.70. Do you think Luke is correct or incorrect? Show why using a number line.
2. The moon Dione takes 2.736915 Earth days to orbit Saturn. Explain in words how
to round the number of Earth days Dione takes to the nearest hundredth.
3. Write two numbers that are between 1.75 and 1.77. Plot these decimal numbers
on a number line and round both decimal numbers to the nearest tenth.
Round decimals using a number line,
Practice Set C Answer Key
1. Luke thinks that the moon Janus - .69466, rounded to the nearest hundredth is
.70. Do you think Luke is correct or incorrect? Show why using a number line.
Luke is incorrect. The benchmarks for this decimal number are .690 and .700. The
midpoint is .695. When placing .694 on the number line, we see that it is 4 away
from .690. While .694 is 6 away from .700.
2. The moon Dione takes 2.736915 Earth days to orbit Saturn. Explain in words how
to round the number of Earth days Dione takes to the nearest hundredth.
Students should be able to talk about the benchmarks and midpoints in order to
show how they round their decimal number. Ex. In order to round to the nearest
hundredth, we need to look at the 2.736 part of the decimal number. The nearest
hundredth below 2.730 and above 2.740 help us to determine which hundredth we
will round to. The midpoint is 2.735, 2.736 is four away from 2.740 and six away
2.730. This means that 2.736 rounded to the nearest hundredth is 2.74. It will take
2.74 Earth days for the moon Dione to orbit Saturn.
3. Write two numbers that are between 1.75 and 1.77. Plot these decimal numbers
on a number line and round both decimal numbers to the nearest tenth.
Students can write decimal numbers between 1.750 - 1.770. Regardless of what
decimal number they choose the rounded answer will be 1.8. Using the number line
below, the tick marks are 1.752, 1.754, 1.756, 1.758, a midpoint of 1.760 and so on.