Question

Eleven members of the Middle School Math Club each paid the same amount for a guest speaker to talk about problem solving at their math club meeting. They paid their guest speaker $1−A−2−. What is the missing digit A of this 3-digit number?

Answer 1

What this question means is that there is a certain number 1x2 that is divisible by 11.

we can simply see what kind of candidates there are. Let's start with 10*11=110.

now, how much is 11*11? it's 121, so not.

12*11? it's 132, and it fits into the question, and the missing number is 3!

so they each paid 12 dollars and gave 132 dollars to the speaker.