Question

How Many 6 Digit Telephone Numbers Can Be Formed If Each Number Starts With 35 And No Digit Appears More Than Once?

Answer 1

We have a 6 digit number

But removing 3 and 5 we have to find total possibilities for 4 digits we have 8 numbers as we cannot count 3 and 5 and the amount of numbers decreases by 1 for number we use so the formula can be given by:

8 × 7 × 6 × 5 = 1680 numbers.