All possible combinations of numbers 0-9 and letters a-z
Answers
there are 26 letters plus 10 digits in the pool of characters, giving us 36 in all. Each position in the string can be any one of these 36 characters, so there are 36 choices for the first character, 36 choices for the second character, and so on for the third and fourth characters.
Based on the rule of the product, that gives us
36×36×36×36=364=1679616 distinct strings of length 4(1)
If the order of the four chosen characters doesn't matter, e.g., if choosing 4,A,Q, and 2 is the same as choosing A,2,4, and Q, then we need to divide the result from (1) by the number of ways four characters can be permuted.
The number of ways of permuting four characters is given by 4!=4×3×2×1=24. This gives us the result, where order does not matter, of
3644!=167961624=69984