Zoe has won some $10 cards as a third prize in a competition she entered. She has decided to give them away to her friends. If she shares them among 3 friends there will be 2 left over, if she shares them among 5 friends there will be 1 left over, if she shares them among 2 friends there will be none left over. What is the smallest number of phone cards she could have won?
If there are n cards, then n is a multiple of 2.
so, you want an even number which is
3a+2 or 5b+1
a must be even and b must be odd.
26 = 3*8+2 = 5*5+1 = 2*13