Numbers 0-9 how many different 13 digit combination can be made?

Answer 1

10,000,000,000,000 This would be the number of permutations on a 13-position combination lock, for example. In the first position there would be one number out of ten possibilities (0-9). Next to any one number there would be any one of ten again. So in the first two positions there are 10 x 10 possible combinations i.e. 10^2 (= 100). In the third position there would be 10 more possibilities against the previous 100 possibilities, i.e. 100 x 10, that is: 10^3 (= 1000). So, for a thirteen digit lock, there would be 10^13 possibilities, which is 1 followed by thirteen zeros, as shown above. Of course, if 'numbers' with leading digits e.g. 0 000 087 654 321, and all zeros, are not counted as valid 'numbers' then there are 13 less possibilities. i.e. There are only 9,999,999,999,987 possible ' numbers'.