3.721 your looking for the nearest hundredths place
1
look at the decimal point as the one then go over till is shows the number 100 under it like this
3.721
100
okay so this would show that the 2 is in the hundredths place
guessing that you are rounding you would look one over to the right and see that there is a 1 in that spot
then you would see if you round up or down like this
0,1,2,3,4 round down
5,6,7,8,9 round up
so then looking you would see that 1 is in the round down place so you answer would be
3.72