Three, thirteen, thirty

Three is the next number after two

            3               

Thirteen is the number between twelve and fourteen. It is the sum of six and seven; one more than twelve, or seven less than twenty.

            13 = 10 + 3                 

Thirty is the number between twenty-nine and thirty-one. Thirty is a number that equals to three times 10.

            30 = 10 +10 + 10 = 3 x 10