September 2024 Brain Puzzler Solution

Q: Which option is larger? No calculators please!

a) the sum of all cubes from 100 to 200

b) the sum of all squares from 1 to 100

squares are the numbers 1^2, 2^2 etc and cubes are 1^3, 2^3 etc

A: The squares.
The only cube from 100 to 200 is 125

But the squares from 1 to 100 include 1 + 4 + 9 + 16 + 25 + 36 + 49 + 64 + 81 + 100 = 385 so the sum of the squares is larger.

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