Mathematics
Grey Kangaroo
2022
4

4

In the equation on the right there are five empty squares. Sanja wants to fill four of them with plus signs and one with a minus sign so that the equation is correct. Where should she place the minus sign?

A. Between 6 and 9 B. Between 9 and 12 C. Between 12 and 15 D. Between 15 and 18 E. Between 18 and 21

Answer

D

SOLUTIOn

The value of 6 + 9 + 12 + 15 + 18 + 21 is 81. Now 81−45 = 36 = 2×18. Therefore, Sanja needs to subtract rather than add 18 and hence the minus sign should be placed between 15 and 18.

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