6.724
6 is in the ones place
7 is in the tenths place
2 is in the hundredths place
4 is in the thousandths place
We want to round to the nearest hundredth, which means we'd either round down to 6.72 or round up to 6.73. This depends on the next digit.
If the next digit is greater than 5, we round up. If it's less than 5, we round down.
Since 4 is less than 5, we round down to 6.72.