Count back to subtract
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Count back to subtract: skill guide
| Objective | Learners subtract a one-digit number from a two-digit number by counting back. |
|---|---|
| Grade | Grade 1 |
| Standard | CCSS.MATH.CONTENT.1.OA.C.5 |
| Difficulty | Developing · Abstract |
| Representation | Number sequence, Numerical equation |
| Practice format | Interactive, account-free practice with immediate feedback |
Objective
Learners subtract a one-digit number from a two-digit number by counting back.
What this practice covers
Each problem is a subtraction equation such as 46 − 3 = □, written with numerals only. The first number is from 21 to 89, and the learner counts back to find how many remain. The first third of problems take away 2 to 5 and stay within the same ten. Later problems can cross back past a ten, and in the second half of a session the number taken away can be as large as 8.
Standards alignment
Supports Common Core: CCSS.MATH.CONTENT.1.OA.C.5 — Relate counting to addition and subtraction.
Who it’s for
This practice is designed for Grade 1 learners subtracting within 100. It is also useful for older learners who want a short review of counting back from a two-digit number.
What to know first
- Learners should count backward from two-digit numbers, read two-digit numerals, and understand subtraction as taking away and finding what remains.
Difficulty and scaffolding
Developing · Abstract stage
Problem representations
- Number sequence
- Numerical equation
Three worked examples
- 38 − 4 = 34: start at 38 and count back 37, 36, 35, 34.
- 53 − 5 = 48: count back 52, 51, 50, 49, 48. The count passes 50 on the way.
- 76 − 8 = 68: count back 8 from 76. The count passes 70 and ends at 68.
Likely misconceptions
- Learners may say the first number as their first count back, as in 38, 37, 36 for 38 − 3, or forget to lower the tens digit after counting back past a ten, as in 53 − 5 = 58. Start counting back with the number just before the first, and keep track of each step on fingers.
Hints and explanations
- 38 − 4 = 34: start at 38 and count back 37, 36, 35, 34.
- 53 − 5 = 48: count back 52, 51, 50, 49, 48. The count passes 50 on the way.
- 76 − 8 = 68: count back 8 from 76. The count passes 70 and ends at 68.
What to practice next
This is the last Grade 1 subtraction practice. The next Grade 1 practice moves to time, starting with reading a digital clock on the hour.
Editorial review
Reviewed by Brilliant’s curriculum team. Exercises are generated within defined difficulty ranges and checked against verified answer rules.
Count back to subtract FAQs
What is the goal of count back to subtract?
The goal is to subtract by counting back from the first number. A learner should be able to explain where the count started and how many numbers were counted back.
Should this practice be timed?
No timer is required. First build accurate, understandable strategies. Speed usually improves naturally as learners recognize groups of ten, familiar facts, and repeated patterns.
What should a learner do after a mistake?
Count back again, starting with the number just before the first number, and keep track of each step. Then check by adding the answer and the number taken away. A short explanation is more valuable than immediately repeating the same guess.
How many problems should be completed at once?
A Quick check has 5 problems and a Practice session has 15. A learner may pause when attention drops. A short, successful session with clear reasoning is more useful than rushing through a longer set.