After cracking the 'sum of cubes' puzzle for 42, mathematicians discover a new solution for 3.

Every so often its good to exercise your brain with a math problem or two that forces you to recall principles you learned decades prior. Can you solve 5+5x5+5 without a hitch?

Fact fluency. Even in an age of universal calculators, all students need to develop automatic, fluent recall of basic math facts, such as addition/subtraction or multiplication tables.