Math Question?

Question

How many positive three-digit numbers are possible?

Answer 1

999 minus the 2 or 1 digit numbers from 1 to 99, making 900 in all.

Answer 2

If you exclude the 1- and 2-digit numbers, then all you have are those from 100 to 999 inclusive.

100 is the the 1st, so 999 (899 more) is the 900th. So:

There are EXACTLY 900 3-digit numbers, those from 100 to 999.

Note: People often MISCOUNT the INCLUSIVE numbers from some beginning number to the some end number, just as they miscount the INCLUSIVE number of days from some date to another date (commonly from a certain day in the week, one week, to the SAME day in the week, the next week), or the INCLUSIVE number of years from some beginning year to some end year. When they miscount like that, they always end up with ONE LESS than the actual number. (I've seen this happen so often, even with people who are remarkably intelligent, that I believe it must be a very common mistake.)

Why is that?:

The great temptation is to simply SUBTRACT the beginning number or date from the end number or date. But that always gives you ONE LESS that the actual answer.

For example, the three digit numbers above clearly go from 100 to 999. If you subtracted them, however, you'd only get 899. The key point is effectively what I did before. If you imagine counting off the successive numbers, 100 is the 1st; and you get that number "1" in "1st" by subtracting 99 from 100, not 100 from 100. So therefore, the key point is to SUBTRACT ONE LESS THAN THE STARTING NUMBER FROM THE END NUMBER. Alternatively, of course, subtract the beginning number from the end number and THEN ADD ONE.

And THAT gives you the total INCLUSIVE number of objects, days, years, whatever, from the beginning to the end.

Live long and prosper.

Answer 3

They are the numbers from 100 to 999
So there are 900 such numbers

Answer 4

999 numbers of course

Answer 5

Does this include fractional portions. Such as, 5.24, for example.