Inverse: addition undoes subtraction
Recognise and use the inverse relationship between addition and subtraction to check calculations and solve missing-number problems
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1858 concepts · 9 subjects
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Inverse: addition undoes subtraction means addition and subtraction reverse each other. If 15 + 7 = 22, then 22 − 7 should return 15. You can check a sum with a related subtraction, and you can find a missing addend by subtracting. We will check one calculation, then solve one box problem with the inverse.
Spend about 12 minutes checking an addition with its related subtraction, solving one missing-number equation using the inverse, and explaining that the operations undo each other.
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Learning resources
Extra practice links — they do not replace Gakuva’s teaching approach.
Toy Theater · Practice link — not the full lesson
Number Bonds — adult-guided supplementary tool
Before you open · source notes
Place a whole and two parts in a number-bond diagram; say the related equations.
Adult must supply questions and judge answers · No automatic marking or saved progress established · Ads · No login/payment in recorded test; access can change.
Before you openA supplementary manipulative, not an automatically marked game. Mobile/touch, audio and drawing tools were not verified.
Opening this link does not save learning or assess mastery.
Parent tips
Try a whole of 9 and one part of 4. Find 5, then explain 4 + 5 = 9 and 9 − 4 = 5. Ask how subtraction undoes addition. This check is parent-led.
Source, access and review notes
Use a number-bond diagram with an adult to explore how addition and subtraction undo one another. Place the whole and its two parts, then say the related equations.
Adult-guided supplementary tool; a manipulative, not an automatically marked game. No automatic correctness feedback, saved progress, or independent learner explanation was established. Parent prompt: “We have 9 altogether and one part is 4. What is the missing part? Show 4 + 5 = 9, then use 9 − 4 = 5 to check. Explain how subtraction undoes the addition.”
Tested number placement required no login or payment. Advertisement labels observed. An adult must supply questions and judge the explanation. Mobile/touch, audio, and drawing tools were not verified. Access and advertisements can change.
Unknown — link only
Check understanding
- Check 15 + 7 = 22 by calculating 22 − 7 = 15
- Use the inverse to solve: □ + 9 = 14, so □ = 14 − 9 = 5
- Explain that addition and subtraction 'undo' each other
“If your child works out 13 + 5 = 18, can they immediately use that to say '18 − 5 = 13' — without having to work the subtraction out all over again?”
Curriculum record
- Type
- Conceptual
- Subject
- Mathematics
- Domain
- Addition & Subtraction
- Age range
- Ages 6–13
Standards