Can you solve this maths brain teaser? A 4×3 grid with numbers and a mystery number—figure out what replaces the question mark!(X/@brainyquiz_) (Also read: This maths puzzle has left internet ...

Start with the smallest numbers and work your way up. It might help if you draw out a grid so you can spot any patterns. Here's one way to find all the prime numbers. 2 is the first prime number.

Coordinates are two numbers used to describe a point's position on a grid. Grids have two axes. The horizontal axis is called the x-axis and the vertical axis is called the y-axis. Coordinates are ...