Answer:
![51.8 \approx52](https://img.qammunity.org/2019/formulas/mathematics/middle-school/kbqx8a55z0m7hnqqfsczani9lbsv1h03xw.png)
to the nearest one.
Explanation:
To round a number to the nearest one is the same as rounding to the nearest unit.
We want to round 51.8 to the nearest one.
Since the number after unit digit is 8 , we round up. That means we need to add 1 to the number in the unit digit and cut off the remaining part to the right of the unit digit.
Therefore
![51.8 = 52](https://img.qammunity.org/2019/formulas/mathematics/middle-school/7ymxadxfy112wh2rd6509bmz5y4iewnqib.png)
to the nearest one.