0, 1, 2, 3, 4, 5
Number of four-digit number starting with 5 is,
= 6 × 6 × 6 = 216
Number of four-digit numbers starting with 45 is,
= 6 × 6 = 36
Number of four-digit numbers starting with 44 is,
= 6 × 6 = 36
Number of four-digit numbers starting with 43 and greaterthan 4321 is,
= 3 × 6 = 18
Number of four-digit numbers starting with 432 and greaterthan 4321 is,
= 4
Hence, required numbers = 216 + 36 + 36 + 18 + 4 = 310.