300

300 = 2² x 3 x 5².

300 is a triangular number, the sum of all positive integers up to 24: 1 + 2 + 3 + . . . + 22 + 23 + 24 = 300.

300 is the sum of twin primes: 149 + 151 = 300.

300 is a number n such that n² (90000) contains exactly two different digits.

In bowling, 300 is the largest possible score.

Source: Wolfram MathWorld