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Education Concept Tracker

A prerequisite knowledge graph of 1590 learning concepts across 8subjects. Track what you've mastered and see exactly what you're ready to learn next — the topics whose prerequisites you've already met. Built on the Marble Open Skill Taxonomy.

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Adding and subtracting (age 7+)

Mathematics · Addition & Subtraction · procedural

Add and subtract numbers with up to three digits using formal written methods of columnar addition and subtraction

What mastery looks like

  • 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

Check your understanding

Can Adding and subtracting (age 7+) set out a sum like '347 + 265' or '512 − 278' in columns and work through it step by step, carrying or borrowing where needed?