If we have the number:
53.864
1. If we round the number to the nearest integer, we have 54 (so it is correct).
2. If we round the number to the nearest tenth, we have 53.9 (correct).
3. If we round the number to the nearest hundredth, we have 53.86 (53.87 is incorrect).
4. If we round to the nearest tens, we have 50.
Therefore, the only incorrect rounding is option C (53.87. It must be 53.86).
