9
90
3 and 9 are both 'natural' numbers.
126
These two numbers: 135 and 180.
9
150 ÷ 9 = 16 r 6 → the first natural number between 150 and 300 divisible by 9 is 9 × 17 (=154)300 ÷ 9 = 33 r 3 → the last natural number between 150 and 300 divisible by 9 is 9 × 33 (=297)→ there are 33 - 17 + 1 = 17 natural numbers between 150 and 300 divisible by 9.
Overall, there are 99900 numbers between 100 and 100000, not including 100 itself. One out of every ten of them ends with a nine, which leaves us with 9990 numbers. It is easier to understand this for small numbers - say we look for the corresponding number between 10 and 100. We have overall 90 numbers, 9 of them end with the digit 9: 19,29,39,49,59,69,79,89,99.
There are 9.
90
8 numbers
3 and 9 are both 'natural' numbers.
126
4, 9, 25, and 49 are all of the numbers between 1 and 100 having 3 factors.
These two numbers: 135 and 180.
9
Between -10 and 10 there are 9 natural numbers if exclusive of the -10 and 10, or 10 if inclusive. The natural numbers are the positive integers starting with 1, ie {1, 2, 3, ...}.