Question: 10 metal rods are laid out in a straight line end to end. Each rod is 70 cm long when rounded to the nearest centimetre. Work out the smallest possible total length of the line of rods.

1. **State the problem:** We have 10 metal rods, each measured as 70 cm when rounded to the nearest centimetre. We want to find the smallest possible total length of all 10 rods laid end to end. 2. **Understanding rounding:** Each rod's length is rounded to 70 cm. This means the actual length $L$ of each rod satisfies: $$69.5 \leq L < 70.5$$ 3. **Smallest possible length of one rod:** The smallest length that rounds to 70 cm is just above or equal to 69.5 cm. 4. **Smallest total length of 10 rods:** Since there are 10 rods, the smallest total length $T$ is: $$T = 10 \times 69.5 = 695$$ 5. **Final answer:** The smallest possible total length of the line of rods is **695 cm**.