The answer will usually depend on the number of significant figures in the numbers from which there numbers were derived.
231.57 has five significant figures/numbers. All the numbers in 231.57 are significant.
The least number of significant figures in any number of the problem determines the number of significant figures in the answer.
3 significant figures.
3 significant figures.
2 significant figures.
It has five significant figures.
4 significant figures
7 significant figures.
2 significant figures.
3 significant figures.
5 significant figures.