Question

Show how to make one addend the next tens number.

24 + 18

Answer 1

I do not understand your question but perhaps:

24 = 20 + 4
18 = 20 - 2
so
24 + 18 = 20 + 20 + 4 - 2
= 40 + 2
= 42
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or
24 = 20 + 4
18 = 10 + 8
so
24 + 18 = 20 + 10 + 4 + 8
= 30 + 10 + 2
= 42 again, remarkable