1.18 √18 = 54 √ 2 (simplified to the simplest form), so rt=54*2= 108.

2. A (5) 5-2 * A (4) 4 =120-48 = 72a (5) 5 is a full array of five cards. When 3 is at both ends, there are four full arrays of 1245 cards respectively, so it should be subtracted.