When comparing decimals, align the decimal points. Compare digit by digit from the left.

All numbers have the same whole-number part (6). Compare the decimal parts:
6.10	=	6 and 10 hundredths
6.30	=	6 and 30 hundredths
6.01	=	6 and 1 hundredth
6.03	=	6 and 3 hundredths
Smallest decimal part is 0.01, so 6.01 is the smallest.