Hello guys, i need some help with ideas for a math fair. I'm looking for a interesting and uncommon math question or puzzle with solution involved math,.

So if you have any math puzzle feel free to share with me, i appreciate your help XD.

I actually have this one math question that i would like to do in the math fair but i cant remember what the steps are i only remember the solution.

Well the following steps are what i roughly remember and hopefully someone will tell me the correct steps

step 1: pick 2 numbers between 10-99 and then multiply them together, have your friend doing the same thing but with different numbers

step 2: multiply the answers you both got

step 3: after you multiply both answers, you hide one number from the answer then you tell the rest of the numbers

and have someone guess the number you hided

solution: each pair add up to 9 (what it mean is 1+8=9, 2+7=9 3+6=9 4+5=9 9+0=9)