答案：(a) $266$ (b) $265.4$ (c) $270$
- $265.473 = 266 \text{ (上捨入至最接近的個位)}$
- $265.473 = 265.4 \text{ (下捨入至一位小數)}$
- $265.473 = 270 \text{ (捨入至二位有效數字)}$
