mathmath333 one year ago Counting question

1. mathmath333

\large \color{black}{\begin{align} & \normalsize \text{How many numbers lying between 100 and 1000 }\hspace{.33em}\\~\\ & \normalsize \text{can be formed with the digits 0, 1, 2, 3, 4, 5,}\hspace{.33em}\\~\\ & \normalsize \text{ if the repetition of the digits is not allowed?}\hspace{.33em}\\~\\ \end{align}}

2. xapproachesinfinity

I'm in counting principles

3. xapproachesinfinity

not good *

4. mathmath333

lol what u want to say

5. ParthKohli

Let's just take three-digit numbers (1000 won't be counted anyway). _ _ _ Whenever repetition is not allowed, we reduce the number of choices by 1 for each subsequent blank. The leftmost blank allows 1, 2, 3, 4, 5 so 5 numbers. The second blank allows 4 numbers but zero is also included, so 5 numbers. The last blank allows 4 numbers. The total number is 5 * 5 * 4 = 100.