Answer:
12.102, 12.012, 12.01, 12.001
Explanation:
Since all of the numbers have the same numbers in the tens and ones places, the first place we need to compare is the tenths. The number with the greatest digit in the tenths place is 12.102, so it is first. The other numbers have a zero in the tenths place, so we move to the hundredths. 12.012 and 12.01 both have a one in the hundreds place, so we need to look at the thousandths. 12.012 is greater because it has a two in the thousandths place instead of a zero like 12.01, so it goes next, then 12.01, leaving 12.001 as the least.