Answer:
Step-by-step explanation:
The pair members cannot be multiplied. Look at the last numbers that are prime starting with eleven
What are you going to pair these primes with
11 13 17 19
So they must be added (or maybe subtracted).
1 19
2 18
3 17
4 16
5 15
6 14
7 13
8 12
9 11
and 20 which no matter how you do this, there will be 1 card left over.
Each of them adds to 20 so the LCM is 20
