If you want to round 98.155 to the nearest tenth, it is 98.2.
The 1 is in the tenths place.
If the number to the right of it is 5 or more, round up.
If the number to the right of it is 4 or less, round down.
In this case, you round the digit in the tenths place up because the digit in the <em>hundredths</em> place is 5+.
