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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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Missing number problems (age 7+)

Mathematics · Addition & Subtraction · procedural

Solve addition and subtraction problems including missing-number problems, using number facts, place value, and more complex methods

What mastery looks like

  • Solve a missing-number problem such as 245 + ? = 380
  • Choose an appropriate method (mental, written, or combination) based on the numbers
  • Solve multi-step problems combining addition and subtraction of three-digit numbers

Check your understanding

Can Missing number problems (age 7+) work out sums with a hidden number — like '? − 38 = 24' or '53 + ? = 91' — by thinking carefully about what the equation is asking?