I consider it an amazing though very challenging puzzle: 1 2 3 4 5 = 5 4 3 2 1 One must insert exactly five pluses (i.e. five addition signs) somewhere between those ten displayed figures in such way that it becomes a true mathematical equality. Also, you can't rearrange/transpose the figures; no...

How many times does the digit $0$ occur in the list of numbers from $1$ to $10^{100}$, inclusive? Computers are allowed, but can you solve it without one?

Combine digits you have into numbers and perform mathematical operations with them to get the rest of the digits. You may use all mathematical operations. You start with 0. Example: You have digits 0, 1, 8. You perform the following operation: 10 - 8 = 2. You have obtained 2. Rules: You may us...

This puzzle is part of the Puzzling Stack Exchange Advent Calendar 2023. The accepted answer to this question will be awarded a bounty worth 50 reputation.< Previous Door Next Door > It's the annual charity softball game at the North Pole. With this year's game falling on December 6 - Finnish Ind...

I'm wondering if it is possible to make a 3x8 grid using 6 tetrominoes, 2 Is, 2 Ls a Z skew and square tetronimoe. I believe it may be impossible but would like to know why. Thank you