C.3 Count backward on a number chart from 120 to 0
What is counting backward
Counting backward is saying numbers in reverse order, from a larger number to a smaller number. It helps us understand number sequence and prepares us for subtraction.
- Counting backward from 5: 5, 4, 3, 2, 1, 0
- Just like walking down stairs, we go from the top step (a bigger number) to the bottom step (a smaller number).
We always start with the largest number and say the next smallest number.
Using a number chart to count backward
A number chart is a grid that shows numbers in order. We can use it as a map to find the number that comes before.
- Find your starting number (like 120).
- To go backward by 1, move to the number to the left on the same row.
- When you reach the start of a row (like 111, 101, 91...), move up to the previous row and go to the last number on the right.
- Continue until you reach 1.
The number chart is a helpful tool. With practice, you will be able to count backward without looking!
Patterns when counting backward
Looking for patterns helps us count faster and more accurately. Patterns are sequences that repeat.
- Decades (Groups of Ten): 120, 110, 100, 90, 80... The tens digit decreases by 1.
- Within a Decade: 45, 44, 43, 42, 41, 40. The ones digit decreases by 1 until you reach a "0".
- Crossing 100: 103, 102, 101, 100, 99, 98... This is an important place to practice!
Hearing the rhyme in the numbers (like "thirty-nine, thirty-eight") can help you remember the pattern.
Counting backward from any number
You don't always have to start at 120. You can start counting backward from any number on the chart.
- Start at 47: 47, 46, 45, 44...
- Start at 100: 100, 99, 98, 97...
- Start at 21: 21, 20, 19, 18...
Pay close attention when you pass a "ten" (like from 40 to 39) or a "hundred" (like from 100 to 99).
Why we learn to count backward?
Counting backward is not just a skill by itself. It is a foundation for other important math concepts.
- Subtraction: 8 - 3 means "start at 8 and count back 3 steps." (8...7, 6, 5). The answer is 5.
- Finding Differences: "How many days until the field trip?" You can count backward on a calendar.
- Problem Solving: "If I have 15 stickers and give 2 away, how many are left?" Count back 2 from 15.
Mastering counting backward makes learning subtraction much easier!
Common Core alignment: CCSS.MATH.CONTENT.1.NBT.A.1 – Count to 120, starting at any number less than 120. In this range, read and write numerals and represent a number of objects with a written numeral.
Notes for teachers
This free lesson is aligned with CCSS.MATH.CONTENT.1.NBT.A.1, extending the standard to include counting backward from 120, a critical prerequisite for subtraction and working with number lines.
All content is 100% free, student-safe, and designed for classroom and home use. Encourage students to use physical number charts, number lines, and hand motions (pointing) to reinforce the skill kinesthetically.