Divide 9000 by 8 with three halvings

Question

Dividing by 8 is one of the safest mental operations, no long division needed. Solve in your head. What is 9000 \div 8? Aim: under 10 seconds.

Accepted Answer

Since 8 = 2^3, halve three times: 9000 	o 4500 	o 2250 	o 1125. So 9000 \div 8 = \mathbf{1125}. Each halving is easy: half of 9000 is 4500, half of that 2250, half again 1125. Check: 8 	imes 1125 = 9000. Correct. Takeaway. Dividing by any power of 2 is repeated halving, by 4 is two halvings, by 8 is three, by 16 is four. Halving is far less error-prone than long division.

Divide 9000 by 8 with three halvings

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