How many 5-digit numbers can be formed using the digits 0 1 2 3 4 5 6 if repetitions are not allowed?

Answer 1

288

000, 001, 002, 003, 004, 005, 006, 010, 011, 012, 013, 014, 015, 016, 020, 021, 022, 023, 024, 025, 026, 030, 031, 032, 033, 034, 035, 036, 040, 041, 042, 043, 044, 045, 046, 050, 051, 052, 053, 054, 055, 056, 060, 061, 062, 063, 064, 065, 066

x 6

Unless you mean all numbers in the string must be unique, excluding numbers like 000 and 001, then it's

180

or

012, 013, 014, 015, 016, 021, 023, 024, 025, 026, 031, 032, 034, 035, 036, 041, 042, 043, 045, 046, 051, 052, 053, 054, 056, 061, 062, 063, 064, 065

x 6

Answer 2

2520 numbers.