# Number bonds

Recall number bonds (addition and related subtraction facts) within 20

Builds on: Number bonds to 9 (hard, https://ai.page/c/number-bonds-to-9/en.md), Fluent adding and subtracting within 5 (hard, https://ai.page/c/fluent-adding-and-subtracting-within-5/en.md)

Concept id: number-bonds. Subject: maths. Licence: CC BY-SA 4.0.

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