## CHAPTER 6: ADDITION AND SUBTRACTION

**Lesson 3: Adding 3-Digit Numbers **

**Goal**

Solve addition problems by grouping hundreds, tens, and ones.

**Instructions for Use**

Estimator Four allows you to estimate or solve addition problems while playing “Connect 4” against someone else. This is a two-player game.

Select “60 seconds” for “Time Limit,” “Addition” for the “Problem Type,” then click “Start Game.” Below the grid, the player whose turn it is (Player Red) will be indicated. Click “Ready” to see the first problem below the grid. Estimate or sum up the answer, then type it in the white box and click “Answer.” If the answer is correct, click a column on the grid to place a game piece into. Then Player Black takes her or his turn answering a question and placing a game piece onto the grid. When one player has four pieces lined up in a row, he or she wins the game.

Base Blocks allows you to build different models of given numbers using base ten blocks.

Use base ten blocks to represent a 3-digit number. Click blocks at the top of the chart so that they appear in the columns below. You may use 100s, 10s, or 1s. To delete one of the blocks, click and drag it into the garbage bin at the bottom right of the chart. To clear the chart, click “Clear.”

Tic-Tac-Toe Squares — Addition has you answer addition problems involving 3-digit numbers to mark squares on a tic-tac-toe board.

Choose an addition problem on the tic-tac-toe board to answer, and type your answer in the box below the problem. Click “Go” beside your answer to check it, then click “Continue” to see which spot the computer marks off. Try to make a line of three Xs by continuing to choose other addition problems on the board to answer.