2
1000
90. all the numbers from 10 through 99
The two numbers 10 and -1: 10 × -1 = -10 10 + -1 = 10 - 1 = 9
four, five, nine :)....and zero
2
The answer is 20C10 which is 20!/[10!(20-10)!] = 184756
When you spell out the words for numbers 1-10 four of the numbers have three letters. (one two six ten)
They are: 4 6 8 9 and 10
2 3 5 7.
Add them up.
1000
90. all the numbers from 10 through 99
OTTFFSSENT is the letters represent the first letter of the numbers 1 through 10
55
Not even = odd. 1, 3, 5, 7, 9, 11, 13, 15, 17, 19 10 numbers (20 / 2 = 10).
The two numbers 10 and -1: 10 × -1 = -10 10 + -1 = 10 - 1 = 9