I have a circular necklace with 18 beads on it. All the beads are different. Making two cuts with a pair of scissors, I can divide the necklace into two strings of beads. If I want each string to have at least 6 beads, how many different pairs of strings can I make?
+636 There are four types we can make
The solution will be the sum these values: 18+18+18+9=63
