Adding and subtracting (age 7+)
Add and subtract numbers with up to three digits using formal written methods of columnar addition and subtraction
Lesson
Set out your lesson
Use aligned written columns, equal-value exchanges, and inverse checks.
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Before teaching
Use this short check, then start teaching.
R1. Write 47 as tens and ones. R2. Start with 3 tens and 2 ones. Exchange exactly one ten for ones. How many tens and ones remain? R3. Work out 8 + 7 and 15 − 8.
R1. Tens:
R1. Ones:
R2. Tens:
R2. Ones:
R3. 8 + 7:
R3. 15 − 8:
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1 approach
Use aligned written columns, equal-value exchanges, and inverse checks.
Use aligned written columns, equal-value exchanges, and inverse checks.
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Learning resources
Extra practice links — they do not replace Gakuva’s teaching approach.
Illustrative Mathematics · Practice link — not the full lesson
Boys and Girls, Variation 2
Before you open · source notes
A second boys-and-girls story builds adding and subtracting with unknowns. Not every decimal calculation.
Free, no sign-in. A teacher solution is on the same page, so use the student view with your child.
Before you openAsk the learner to name the unknown and solve with addition or subtraction.
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Source, access and review notes
Public Illustrative Mathematics task page. The .html address responds HTTP 308 to this URL. An anonymous GET of this URL on 2026-11-12 returned HTTP 200 with no login or payment prompt. Where a teacher solution is present, it is on the same page as the student task; this check did not find a separate locked student view. An adult can use the student view section and should not read a solution aloud. Advertising was not observed in the fetched HTML text; that is not a browser, device, or ad-free guarantee. This is a paper or discussion task, not an automatically marked interactive game. Opening the link does not save practice or assess mastery. Diagrams on the page use missing or filename-only alt text, so they are not an accessible image equivalent. Accessibility still depends on an adult describing the picture.
Illustrative Mathematics. “Boys and Girls, Variation 2.” Licensed CC BY-NC-SA 4.0. External task; Gakuva does not copy, host, embed, or redistribute it.
CC BY-NC-SA 4.0 — link only
Check understanding
- Set out a columnar addition correctly with digits aligned by place value
- Carry out columnar subtraction with exchange (borrowing) when needed
- Check the answer using the inverse operation or estimation
“Can your child set out a sum like '347 + 265' or '512 − 278' in columns and work through it step by step, carrying or borrowing where needed?”
Curriculum record
- Type
- Procedural
- Subject
- Mathematics
- Domain
- Addition & Subtraction
- Age range
- Ages 7–9
Standards