### Home > MC1 > Chapter 1 > Lesson 1.1.3 > Problem 1-22

Study the dot patterns in parts (a) and (b) below. Assume that each pattern continues to increase by the same number of dots and in the same locations for each figure. For each pattern, sketch the 4th and 5th figures and then predict how many dots will be in the 100th figure.

Look at the vertical dots. How are they growing? What about the horizontal ones?

With each new figure, the vertical line gets one dot on the top and one dot on the bottom. The horizontal line gets one dot on the right side each time.

How can you find each figure number in the number of dots? Can you find groups of two dots in the second figure? Can you find groups of three dots in the third figure? Use this to help you with the 100th figure.

The 100th figure will have 301 dots.

How many columns of two are in each figure? How many would you expect in figures 4 and 5? What about Figure 100?

For each pattern,

**explain**how you made your prediction for the 100th figure.Did you use numbers or diagrams? How do you know that your answer makes sense?

Use the eTool below to model the 4th and 5th figure for parts (a) and (b).

Click the link at right for the full version of the eTool: MC1 1-22 HW eTool