Generally, when spelt out in words in English, you hyphenate the numbers between 20 and 99 which have digits other than 0 in the units column - for example, twenty-one, twenty-two, twenty-three.... ninety-eight, ninety-nine.
-99
There are 900 three-digit numbers, all of which are between 99 and 3,000.
15 + 17 + 19 = 3 x 17 = 51
8 ... they are 20, 30, 40, etc on up to 90
There are 90 whole numbers between 10 and 99, inclusive. This is calculated by subtracting the lower limit (10) from the upper limit (99) and then adding one: (99 - 10 + 1 = 90). Thus, the whole numbers range from 10 to 99.
Every integer from 20 to 99 qualifies; therefore there are 99 - 19 or 80 such numbers.
In general, the numbers form 21-99 are hyphenated; ninety-seven
There are 49 even numbers between 1 and 99.
First number is 20 and last is 99 so 20 = 1 then 21 = 2 then 29 = 10 So from 29 take 19 to make 10 then apply to 99 as in 99 - 19 = answer 80
-99
It is hyphenated, as asked, eighty-four. Numbers from 21 to 99 are hyphenated when spelled out, as are combined ordinal forms such as one hundred-thousandth, one fifty-fifth, and so forth.
99
There are 900 three-digit numbers, all of which are between 99 and 3,000.
15 + 17 + 19 = 3 x 17 = 51
8 ... they are 20, 30, 40, etc on up to 90
There are 99 numbers between 0 and 100.
There are 900 three digit numbers between 99 and 3,000 - ranging from 100 to 999