Complete addition patterns
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Complete addition patterns: skill guide
| Objective | Learners find the missing number in a pattern that counts up by 10. |
|---|---|
| Grade | Grade 1 |
| Standard | CCSS.MATH.CONTENT.1.NBT.C.5 |
| Difficulty | Developing · Abstract |
| Representation | Number sequence, Numerical equation |
| Practice format | Interactive, account-free practice with immediate feedback |
Objective
Learners find the missing number in a pattern that counts up by 10.
What this practice covers
Each problem shows five numbers that count up by 10, such as 24, 34, 44, 54, 64, with one number missing. All the numbers are from 10 to 99. Early in a session the blank is always the last number. In the middle of the session it can be any number after the first, and near the end it can be any of the five.
Standards alignment
Supports Common Core: CCSS.MATH.CONTENT.1.NBT.C.5 — Given a two-digit number, mentally find 10 more or 10 less.
Who it’s for
This practice is designed for Grade 1 learners working with two-digit numbers from 10 to 99. It is also useful for older learners who want a short review of counting up by 10.
What to know first
- Learners should read two-digit numerals and know that the tens digit tells how many tens are in a number.
Difficulty and scaffolding
Developing · Abstract stage
Problem representations
- Number sequence
- Numerical equation
Three worked examples
- 13, 23, 33, 43, □: each number is 10 more than the one before it, so the blank is 53.
- 26, □, 46, 56, 66: the tens digit goes up by one at each step, so the blank is 36.
- □, 50, 60, 70, 80: the blank comes first, so it is 10 less than 50, which is 40.
Likely misconceptions
- Learners may change the ones digit instead of the tens digit, or count on by 1 instead of by 10. When the blank comes first, some learners add 10 again instead of finding the number that is 10 less than the next one. Compare two neighboring numbers, name the step, and check that every number has the same ones digit.
Hints and explanations
- 13, 23, 33, 43, □: each number is 10 more than the one before it, so the blank is 53.
- 26, □, 46, 56, 66: the tens digit goes up by one at each step, so the blank is 36.
- □, 50, 60, 70, 80: the blank comes first, so it is 10 less than 50, which is 40.
What to practice next
Next, add three numbers by finding two that make 10 first, then adding the third.
Editorial review
Reviewed by Brilliant’s curriculum team. Exercises are generated within defined difficulty ranges and checked against verified answer rules.
Complete addition patterns FAQs
What is the goal of complete addition patterns?
The goal is to find the missing number in a pattern that counts up by 10. A learner should be able to name the step between two numbers and explain why only the tens digit changes.
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?
Read the pattern aloud, name the step between two numbers that are both shown, and use that step to fill the blank. 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.