Table­s use­ number families. Take a look at this table showing how many miles two joggers ran in two hours.

Miles Jogged

Hour 1

Hour 2

Total

Jogger #1

3

2

5

Jogger #2

4

2

6

Total

7

4

11

The rows and columns in this table work just like number families. In the rows, the greatest (largest) number is on the far right. That's the sum (answer). The lesser (smaller) numbers are to the left of the greatest number. The lesser numbers added together equal the greatest number. For instance, the first row tells how many miles Jogger #1 ran in the first hour, in the second hour, and in sum. She ran 3 miles in the first hour, 2 miles in the second hour, and 5 miles altogether. In this row, 3, 2, and 5 are all part of a number family. The addition facts and subtraction facts are 3 + 2 = 5, 2 + 3 = 5, 5 - 2 = 3, and 5 - 3 = 2.

Columns tell about number families, too. The greatest number is at the bottom. That's the sum. The lesser numbers are above the greatest number. The numbers added together equal the greatest number. For instance, the first column tells how many miles were run in the first hour by Jogger #1, Jogger #2, and altogether. Jogger #1 ran 3 miles, and Jogger #2 ran 4 miles. The two of them ran a total of 7 miles in the first hour. In this case, 3, 4, and 7 are all part of a number family. The addition and subtraction facts are 3 + 4 = 7, 4 + 3 = 7, 7 - 3 = 4, and 7 - 4 = 3.