Question

A code has 6 digits. You can type in 0~9 for your code. How many different combinations of codes can you make if you can repeat digits? How many different combinations of codes can you make if you can not repeat digits?

Answer 1

combinations
10 choices per slot
10^6=1000000
1 million different ways if can repeat

if cannot repeat
10*9*8*7*6*5=151200 ways without repat