Riddle answer : As many as you like -- (100-10) will always equal 90.
However, if it isn't a riddle, the answer would be 10 to reach 0. You could continue to subtract 10 an infinite number of times, yielding an increasing negative value.
You can subtract 10 from 100 ten times before reaching zero. Each subtraction reduces the number by 10, so after ten subtractions, you will have 100 - (10 * 10) = 0. Therefore, you can subtract 10 from 100 ten times in total.
10 times
5
Once! After you have subtracted it once, you are subtracting 100 from 1900, and then 100 from 1800 and on and on
10
10 times.
-100
10 times
You can subtract 10 from 50 five times. Unless you're feeling rebellious and want to break the rules, then go ahead and subtract 10 as many times as your heart desires. Just don't come crying to me when you're left with a negative number and a bruised ego.
10 times.. because.. 100 * 10 = 1000
ten times
100 is ten times more than 10