Mathematical arithmetic rounding $1$

Question

What is an example of $4$-digit arithmetic rounding:
$ \text{ }\\ \text{a)}\\ 11.2468 = 11.25\\ \text{ }\\ \text{b)}\\ 0.25632 = 0.256\\ \text{or}\\ 0.25632=0.2563\\ $

Can you explain what is correct in example $\text{b)}$?

Answer 1

Imagine multiplying everything by 10: 2.5632 rounds to 2.563. It's the same if we didn't multiply by 10: 0.25632 rounds to 0.2563. Similarly,0.025632 rounds to 0.02563. The rounding process is invariant under multiplying or dividing by powers of 10.