Mental strategies including estimation to add/subtract whole numbers up to 20
30 tutor-authored questions for this Ontario curriculum expectation, ordered easiest to hardest, every one with a full worked solution. Work through all 30 with your weekly-lesson access code.
Sample: the first question, solved
Add mentally: 8 + 5.
📘 Worked solution
✓13.
And one from the hard end
Explain two different mental strategies for solving 17 + 6, and check that both give the same answer.
Solution shown after you try it in practice mode.
Work through all 30, easiest to hardest
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