You add extra zeroes until all numbers have the same quantity. in this case, 2.303 has three numbers after the decimal, so the other three number need it too. 2.300, 2.330, and 2.030. now that you have all of them looking the same now, you can tell which is least and work from there: 2.030 is the least, then 2.300, 2.303 then 2.330 is the largest.
