Answer:
1. it goes : 1,2,4,5,10,20,25,50,100. so it is reversed once it gets to 10(which is multiplied by itself)
2. it goes: 1,3,9,27,81. since it is a square number it is only multiplied by 9 once before repetition.
3. a square number like 36 has the same concept as the 81, so when it gets to 6 × 6 it begins the reversion.
4. a non sqaure number like 28 goes 1,2,3,4,7,19,28. so it's right after the 4×7 it begins the reversion.
5. for example,3 goes 1,3 so I believe there is no need for repetition since there is only one pair of numbers as factors.
hope this helps
