## CHAPTER 3: ADDITION AND SUBTRACTION

**Lesson 7: Subtracting Numbers Close to Hundreds or Thousands **

**Goal**

Use mental math to subtract.

**Instructions for Use**

**Subtracting Three Digit Numbers**

To use Subtracting Three Digit Numbers, read the directions, scroll down to “Practice”, and click on “Start”. A pair of numbers will display at the left of the equals sign as a timer counts elapsed time in the “Report Totals” box below. Enter your answer in the box right of the equals sign and click on “check”. If correct, a new pair of numbers will be displayed. If not, an error box will display the correct answer. Click “OK” to resume play. You can vary the game by scrolling down to “Play” and clicking on one of the 3 yellow boxes on the left.

**QUIA Math Journey**

To use QUIA Math Journey, read the directions, click “3-digit numbers” and “4-digit numbers” under

“Addition” or “Subtraction”, and click on “Begin the Game”. A problem will be displayed for you to solve. Your objective is to fly around the world, city by city, by solving problems like this. Although the problems must be answered exactly, estimate to check that each answer that you input into the empty answer box is reasonable before clicking on “Check Answer”. If an answer is right, you will score air distance travelled and receive a new problem. If it is wrong, you will miss your flight and be shown the correct answer. Click on “Continue” to get a new problem. If you miss three flights, the game ends. To play a new game at any time, click on “Start over”.