Skip counting by 2s, 5s and 10s

What is this skill?

Skip counting means counting forward by the same amount each time instead of by ones. In first grade, children practice counting by 2s (2, 4, 6, 8), 5s (5, 10, 15, 20) and 10s (10, 20, 30, 40). A typical question shows the start of a pattern, such as 15, 20, 25, and asks for the next number.

Each count has a pattern children can notice. Counting by 10s from a multiple of ten always ends in 0. Counting by 5s ends in 5 or 0, alternating. Counting by 2s from 2 lands on the even numbers. Seeing these patterns turns skip counting from memorizing a list into understanding a rule.

Why it matters

Skip counting makes counting large groups faster and more accurate: pairs of socks by 2s, fingers by 5s, coins by 10s. It is also the bridge to multiplication. A third grader working out 6 × 5 often starts by counting "5, 10, 15, 20, 25, 30," and children who already skip count fluently find multiplication much more approachable.

Counting by 5s and 10s also supports telling time to five minutes and counting money, both of which come up in second grade. Counting by 2s is the first step toward understanding even and odd numbers, another second grade topic, because the numbers you land on when counting by 2s from 2 are exactly the even numbers.

Common mistakes

• Slipping back into counting by ones partway through, for example 5, 10, 15, 16. Saying the sequence rhythmically or clapping on each number helps keep the step size steady.
• Losing the pattern after a decade change, such as 45, 50, 60 when counting by 5s. Looking at the ones digit, which alternates 5 and 0, gives a way to check.
• Being able to recite the sequence from the beginning but not continue it from the middle. Practice starting from different numbers, like 35 or 14, not just from the start.

How to help at home

• Count real groups: shoes by 2s, fingers on everyone's hands by 5s, ten-packs of crayons by 10s. Then count the same group by ones to check that the answer matches.
• Use a hundred chart and color the numbers you land on when counting by 2s, 5s or 10s. The colored patterns, columns and stripes, show the rules clearly.
• Count coins: nickels by 5s and dimes by 10s. Handfuls of change make great practice.
• Turn it into a movement game: jump, clap or step on every number in the count. Physical rhythm helps young children hold the pattern.

Worked examples

These are real questions from the Tutorsaurus skip counting by 2s, 5s and 10s practice, with the answers worked out.

1. Example 1

   Count by 5s: 10, 15, 20, …

   Answer: 25. Adding 5 each time: 10, 15, 20, 25.

2. Example 2

   Count by 10s: 30, 40, 50, …

   Answer: 60. Adding 10 each time: 30, 40, 50, 60.

3. Example 3

   Count by 10s: 50, 60, 70, …

   Answer: 80. Adding 10 each time: 50, 60, 70, 80.