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

What seemed like a regular grade school math problem had people totally stumped on social media.

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?

Share or comment on this article: Easy looking math equation proves tricky for people - do you know the rule to solve the sum in 30 seconds?

After years of work, there was only one number left below 100 that hadn't been proven to be the sum of three cubes. A million+ hours of worldwide supercomputer time later, even mighty 42 has fallen.

Both of those seem high to me, since the sum of the first 10^6 terms of the series is < 137 and the terms get smaller as they progress.