Fundamentals of chemistry

Suppose that 8.56 is the result of an operation carried out with the calculator. If the number of significant figures is only two, we should return 8.5. But since the third digit is greater than 5, the second digit is rounded to 6. The final result is 8.6.

When the number to be removed is less than 5, the preceding digit does not change. If 5 is the number to be eliminated, the preceding digit is replaced by the nearest even number.

Let's see examples:
8.48 rounds to 8.5; 2.43 rounds to 2.4; 2.45 rounds to 2.4; 2.35 rounds to 2.4.