Multiplication follows four reliable rules. See them proven with a grid of dots you can rotate, group, and even make disappear.
You can multiply two numbers in either order and get the same product. An array of dots proves it — rotate it 90° and you're just looking at the same dots from a different direction.
When multiplying three or more numbers, it doesn't matter which two you multiply first — the final product is always the same.
Two special numbers change what multiplication does: 1 leaves everything exactly the same, and 0 wipes everything out.
Eight questions mixing all four properties — identify which one is being used, or fill in the missing number.