Skip counting by 7 and 49 – Elementary Math

Purpose

To skip count by non-decade numbers.

Materials

None

Overview

To prepare students to use multiples of 7 and 49, start by saying the number 7. Point to individual students and have them add 7 to the previous number until they reach 49. Repeat this activity, but this time ask students to count by 49 up to 343. Students may initially think that it’s very hard to mentally add 49. If no one offers a strategy, help students see that adding 49 can be thought of as adding 50 and then subtracting 1. So, to add 49 to 49, a student might reason that 49 + 50 = 99, so 49 + 49 must be one less, or 98. Similarly, 49 + 49 is 2 less than 50 + 50.

About the sequence

Part 1 asks students to skip count by 7 until they reach 49. Part 2 starts off counting by 50 from 0 to 200 for a quick reference point. Then, students skip count using multiples of 49 from 0 to 343. You may need to remind students that 49 is one less than 50 and 98 is two less than 100 (50 + 50), and 147 is 3 less than 150 (50 + 50 + 50).

Part 1

Let’s count by 7 from 0 to 49. (Extend counting to 84 if students are eager to continue skip counting.)

0, 7, 14,…35, 42, 49

While children are enjoying their building of mastery, feel free to repeat. When children are eager for more, try Part 2.

Part 2

Let’s count by intervals of 50 from 0 to 300.

0, 50, 100…250, 300, 350

If we can count by 50, then we can count by 49 because it’s only one less than 50. Then, 98 is two less than 100 (50 + 50). So let’s count by 49 from 0 to 343.

0, 49 (50 – 1) , 98 (50 + 50 – 2), 147 (50 + 50 + 50 – 3), 196 (200 – 4), 245 (250 – 5), 294 (300 – 6), 343 (350 – 7)