Question

The last part of a telephone number has four digits, e.g. 7814 1487 2103 2772
The last part of the telephone number can start with any digit apart from zero. The other three digits can be any number. How many four digit numbers are there?

Answer 1

9*10*10*10

Answer 2

Thank you, sorry to be slow but, is that 9,101,010? Can't believe it is this simple!

Answer 3

Each number has ten possible values, 0-9, and you find the possible number of combinations by multiplying them together. So with 2 numbers it would be 10 x 10 = 100 possibles. Then x another 10 for three numbers = 1000. For the final number, if you can't have zero it's only x 9 this time, so the total would be 9000 possible numbers.