## CHAPTER 1: NUMBER RELATIONSHIPS

**Lesson 2: Divisibility by 3 and 9 **

**Goal**

Apply divisibility rules to determine if 3 or 9 is a factor of a whole number.

**Instructions for Use**

**Divisible by 3**

To use Divisible by 3, read the rule, scroll down to “Practice”, and click on the “Start” button. A number will be displayed in the box below the “Start” button and a timer will begin counting elapsed time in the “Report Totals” box. Click on either the “Yes” or “No” box depending on whether you think the number is divisible by 3 or not. If your answer is correct a new number will be displayed. If not, an error box will pop up with the correct answer. In this case, click on the “X” to continue the game for as long as you like. You can also vary the game by scrolling down to “Play” and clicking on one of the choices shown in the 3 yellow boxes at left.

**Divisible by 9**

To use Divisible by 9, read the rule, scroll down to “Practice”, and click on the “Start” button. A number will be displayed in the box below the “Start” button and a timer will begin counting elapsed time in the “Report Totals” box. Click on either the “Yes” or “No” box depending on whether you think the number is divisible by 9 or not. If your answer is correct a new number will be displayed. If not, an error box will pop up with the correct answer. In this case, click on the “X” to continue the game for as long as you like. You can also vary the game by scrolling down to “Play” and clicking on one of the choices shown in the 3 yellow boxes at left.