The + sign adds two values:
10 + 20 = 30

The - sign subtracts one value from the other:
20 - 10 = 10

The * sign multiplies two values together:
10 * 20 = 200

The / sign divides one value from the other:
20 / 10 = 2

The % sign gives you the remainder after dividing two numbers:
22 % 10 = 2