Answer :
smallest to biggest : 2.01 , 2.1, 2.102, 2.12, 2.21
if it makes it easier....add 0's...like this
2.010
2.100
2.102
2.120
2.210
it might make it easier to see the order they go in
if it makes it easier....add 0's...like this
2.010
2.100
2.102
2.120
2.210
it might make it easier to see the order they go in