When comparing, think of the signs as a crocodile. A crocodile will want to eat greater (bigger) numbers than smaller numbers. So, you can think of it as that way.
2. 0.5 < 0.8 ... 0.8 is greater than 0.5
5. 0.7 = 0.70 ... This is same. 0.70 just has an extra 0 which you don't need.
8. 2.9 > 2.8 ... 2.9 is greater since 9 is bigger than 8.
11. 0.65 > 0.36 ... 65 is greater than 36. Therefore, 0.65 is greater.
14. 4.50 > 4.05 ... 4.50 has a five in the tenth place. 4.05 has five in the hundredth place.
17. 6.01 < 6.1 ... 6.1 has a one in the tenth place. 6.01 has a one in the hundredth place.