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Lesson 10Representing Large Numbers on the Number Line

Let’s visualize large numbers on the number line using powers of 10.

Learning Targets:

  • I can plot a multiple of a power of 10 on such a number line.
  • I can subdivide and label a number line between 0 and a power of 10 with a positive exponent into 10 equal intervals.
  • I can write a large number as a multiple of a power of 10.

10.1 Labeling Tick Marks on a Number Line

Label the tick marks on the number line. Be prepared to explain your reasoning.

A number line with eleven evenly spaced tick marks. The first tick is labeled 0, the last tick is labeled 10 to the seventh power, and the remaining tick marks are blank.

10.2 Comparing Large Numbers with a Number Line

  1. Drag the points to their proper places on the number line. Be prepared to explain your reasoning.
open applet in presentation mode

  1. Discuss with a partner how you decided where each point should go.

  2. Which is larger, 4,000,000 or 75 \boldcdot 10^5 ? Estimate how many times larger.

10.3 The Speeds of Light

The table shows how fast light waves or electricity can travel through different materials:

material speed of light (meters per second)
space 300,000,000
water (2.25) \boldcdot 10^8
copper wire (electricity) 280,000,000
diamond 124 \boldcdot 10^6
ice (2.3) \boldcdot 10^8
olive oil 200,000,000

  1. Which is faster, light through diamond or light through ice? How can you tell from the expressions for speed?

    Let’s zoom in to highlight the values between (2.0) \boldcdot 10^8 and (3.0) \boldcdot 10^8 .

    open applet in presentation mode

  1. Plot a point for each speed on both number lines, and label it with the corresponding material.

  2. There is one speed that you cannot plot on the bottom number line. Which is it? Plot it on the top number line instead.

  3. Which is faster, light through ice or light through diamond? How can you tell from the number line?

Are you ready for more?

  1. Find a four-digit number using only the digits 0, 1, 2, or 3 where:
    • the first digit tells you how many zeros are in the number,
    • the second digit tells you how many ones are in the number,
    • the third digit tells you how many twos are in the number, and
    • the fourth digit tells you how many threes are in the number.

    The number 2,100 is close, but doesn’t quite work. The first digit is 2, and there are 2 zeros. The second digit is 1, and there is 1 one. The fourth digit is 0, and there are no threes. But the third digit, which is supposed to count the number of 2’s, is zero.

  1. Can you find more than one number like this?
  2. How many solutions are there to this problem? Explain or show your reasoning.

Lesson 10 Summary

There are many ways to compare two quantities. Suppose we want to compare the world population, about

7.4 billion

to the number of pennies the U.S. made in 2015, about

8,900,000,000

There are many ways to do this. We could write 7.4 billion as a decimal, 7,400,000,000, and then we can tell that there were more pennies made in 2015 than there are people in the world! Or we could use powers of 10 to write these numbers: 7.4 \boldcdot 10^9 for people in the world and 8.9 \boldcdot 10^9 for the number of pennies.

For a visual representation, we could plot these two numbers on a number line. We need to carefully choose our end points to make sure that the numbers can both be plotted. Since they both lie between 10^9 and 10^{10} , if we make a number line with tick marks that increase by one billion, or 10^9 , we start the number line with 0 and end it with  10 \boldcdot 10^{9} , or 10^{10} . Here is a number line with the number of pennies and world population plotted:

A number line with a point labeled "People" and another point labeled "Pennies."

Lesson 10 Practice Problems

  1. Find three different ways to write the number 437,000 using powers of 10.

  2. For each pair of numbers below, circle the number that is greater. Estimate how many times greater.

    17 \boldcdot 10^8 or 4 \boldcdot 10^8

    2 \boldcdot 10^6 or 7.839 \boldcdot 10^6

    42 \boldcdot 10^7 or 8.5 \boldcdot 10^8

  3. What number is represented by point A ? Explain or show how you know.

    A zoomed in number line where the top and bottom number lines have eleven evenly spaced tick marks. The first tick mark on the top number line is labeled 0 and the last tick mark is labeled 10 to the twelfth power. The remaining tick marks are blank. Two lines extend downward from the eighth and ninth tick marks, pointing to the first and eleveth tick marks on the second number line, representing a zoomed in portion of the first number line. Point A is located on the fifth tick mark, and the remaining tick marks are blank.

  4. Here is a scatter plot that shows the number of points and assists by a set of hockey players. Select all the following that describe the association in the scatter plot:

    a scatter plot showing a strong positive correlation between the number of assists and the number of points over 15 hockey games.
    1. Linear association
    2. Non-linear association
    3. Positive association
    4. Negative association
    5. No association

  5. Here is the graph of days and the predicted number of hours of sunlight, h , on the d -th day of the year. 

    A graph of a curve on a coordinate grid, with the origin labeled “O.” The horizontal axis has the numbers 50 through 350, in increments of 50, indicated. The vertical axis has the numbers 5 through 20, in increments of 5, indicated. The curve begins on the vertical axis at 8 and curves upward and to the right unitl reaching its maximum at the point 180 comma 18. It then curves downward and to the right, ending at the point 365 comma 8.

    1. Is hours of sunlight a function of days of the year? Explain how you know.

    2. For what days of the year is the number of hours of sunlight increasing? For what days of the year is the number of hours of sunlight decreasing?

    3. Which day of the year has the greatest number of hours of sunlight?