Question

How many 5 digot number are there in all

Answer 1

Answer:

That depends a bit on what you mean by a 5-digit number.

I mean, technically 00123 is a 5-digit number, but I guess you’d say that is really just 123 so doesn’t count? And what about negative numbers? Do you count -12345 as a 5-digit number?

Assuming we don’t count leading-zeroes and exclude negative numbers then the range is from 10000 to 99999.

So how many numbers is that? Well you could count them all. That might get a little tedious!

Or you could subtract 10000 from 99999 then add 1.

Or you could look at each digit in turn… Starting at the right-hand end, the final digit can take one out of 10 different values - 0, 1, 2, 3, 4, 5, 6, 7, 8 or 9. Similarly for each of the 3 digits to the left of it. But the first digit can only be taken from 9 different values - because we’re excluding 0.

So our 5-digit number is made up as one digit chosen from 9, followed by one digit chosen from 10, followed by one digit chosen from 10, followed by one digit chosen from 10, followed by one digit chosen from 10.

The number of possibilities are thus 9 x 10 x 10 x 10 x 10

Answer 2

Answer:

99999 it is the largest