Question

How many different six-digit decimal numbers can be formed where the first digit is a 1 or the last digit is a 5?

Answer 1

10000 different numbers

Explanation:

The numbers will have the form 1XXXX5, in this case, the order is important because 123465 is a different number to 123645. To know the total of differents decimal numbers, use the formula of permutation with repetition:

`n^r`

`n` is the number of options,
`n=10`, and
`r` the number of times you have to place a digit,
`r=4`.

`10^4=10000`