Akey code must contain 4 numerals. there are 9 numerals available . using these numerals, how many different key codes may be created ?

How many
if you can repeat the numbers then it is combiniations go to
if you cannot repeat an use only each number once, then go to (permutations)


combinations
4 slots
9^4 is answer isnc you can repeat is answer
9^4=6561 different ones


permutations
slot method
4 slots
9 in 1st
8 in second (1 in first slot
7 in 3rd
6 in 4th
9*8*7*6=3024 ways

if you can repeat numersals then answer is 6561 ways (combinations)

if you cannot repeat then answer is 3024 ways (permutations)

Cisco co cop hop h0 cop go srry cop hop h0 d8