If you are trying to round 18.4 to the nearest tenth, then you already have your answer there: 18.4
The nearest tenth ends up to be just the first number to the right of the decimal point.
20.0
200
It is 5.2 when rounded to the nearest tenths.
65.6
It is then 52.8 when rounded to the nearest tenth
It is then 56.5 when rounded to the nearest tenth
It is 232.4 when rounded to the nearest tenth
It is 12.4 rounded to the nearest tenth
It is 0.8 when rounded to the nearest tenth
It is then 20.2 when rounded to the nearest tenth
4.4
346.21 rounded to the nearest tenth is 346.2.
113.04 rounded to the nearest tenth is 113.0.