Because 2025 = 45² and 45 is a triangle number, we get these lovely sums:
2025 = (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9)²
2025 = 1³ + 2³ + 3³ + 4³ + 5³ + 6³ + 7³ + 8³ + 9³
Pleasingly the next triangle number 55 is 10 more, so get ready for a repeat of this fact in the year 3025.
9 months ago