# Adding and subtracting tens mentally

Add and subtract a two-digit number and tens mentally and using concrete/pictorial representations

Builds on: 10 More or 10 Less (hard, https://ai.page/c/10-more-or-10-less/en.md), The two digits of a two-digit number (hard, https://ai.page/c/the-two-digits-of-a-two-digit-number/en.md)

Concept id: adding-and-subtracting-tens-mentally. Subject: maths. Licence: CC BY-SA 4.0.

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