Add 3 numbers strategically
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Add 3 numbers strategically: skill guide
| Objective | Learners will be able to add three numbers by first finding two that make 10, then adding the third. |
|---|---|
| Grade | Grade 1 |
| Standard | CCSS.MATH.CONTENT.1.OA.A.2 |
| Difficulty | Developing · Abstract |
| Representation | Numerical equation |
| Practice format | Interactive, account-free practice with immediate feedback |
Objective
Learners will be able to add three numbers by first finding two that make 10, then adding the third.
What this practice covers
Each problem shows an equation with three numbers, such as 7 + 3 + 6, and a blank for the total. There is no picture. The prompt asks the learner to look for two numbers that make 10, then add the third. The pair that makes 10 always sits side by side, either first or last. The third number is from 1 to 9, so totals run from 11 to 19. The learner taps the total from five choices.
Standards alignment
Supports Common Core: CCSS.MATH.CONTENT.1.OA.A.2 — Solve addition problems that call for the sum of three whole numbers whose sum is less than or equal to 20.
Who it’s for
This practice is for Grade 1 learners who know the pairs that make 10 and can add 10 and a single digit. It also suits older learners who add every list of numbers from left to right.
What to know first
- Learners should count reliably, read two-digit numerals, and understand addition as joining parts. Problems show numerals only.
Difficulty and scaffolding
Developing · Abstract stage
Problem representations
- Numerical equation
Three worked examples
- For 7 + 3 + 6, 7 and 3 make 10. Then 10 + 6 = 16.
- For 4 + 2 + 8, the pair that makes 10 comes last. 2 + 8 = 10, then 10 + 4 = 14.
- For 5 + 5 + 9, 5 and 5 make 10. Then 10 + 9 = 19.
Likely misconceptions
- Learners may add from left to right and miss the pair that makes 10, especially when the pair comes last. Others find the pair and forget to add the third number. Ask which two numbers make 10, then what is left to add.
Hints and explanations
- For 7 + 3 + 6, 7 and 3 make 10. Then 10 + 6 = 16.
- For 4 + 2 + 8, the pair that makes 10 comes last. 2 + 8 = 10, then 10 + 4 = 14.
- For 5 + 5 + 9, 5 and 5 make 10. Then 10 + 9 = 19.
What to practice next
Next, Add across 10 adds two single-digit numbers whose sum is more than 10, such as 7 + 6.
Editorial review
Reviewed by Brilliant’s curriculum team. Exercises are generated within defined difficulty ranges and checked against verified answer rules.
Add 3 numbers strategically FAQs
What is the goal of add 3 numbers strategically?
The goal is to add three numbers by spotting a pair that makes 10. A learner should be able to name the pair, say 10, and then add the third number to 10.
Should this practice be timed?
No timer is required. First build accurate, understandable strategies. Speed usually improves as learners know the pairs that make 10 by heart.
What should a learner do after a mistake?
After a wrong answer, the learner gets a second try. Cover one number at a time and ask whether the other two make 10. Then add the third number to 10. A short explanation helps more than a quick second 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 one.