Convert the following lengths to millimeters and centimeters: a) 5 cm b) 10 cm c) 13 cm d) 4 1/2 cm e) 51 cm f) 250 mm

$$
5 \text{ cm} \times 10 \frac{\text{mm}}{\text{cm}} = 50 \text{ mm}
$$
The answer is $\boxed{50 \text{ mm}}$.

$$
10 \text{ cm} \times 10 \frac{\text{mm}}{\text{cm}} = 100 \text{ mm}
$$
The answer is $\boxed{100 \text{ mm}}$.

$$
13 \text{ cm} \times 10 \frac{\text{mm}}{\text{cm}} = 130 \text{ mm}
$$
The answer is $\boxed{130 \text{ mm}}$.

$$
4\frac{1}{2} \text{ cm} = 4.5 \text{ cm}
$$

$$
4.5 \text{ cm} \times 10 \frac{\text{mm}}{\text{cm}} = 45 \text{ mm}
$$
The answer is $\boxed{45 \text{ mm}}$.

$$
51 \text{ cm} \times 10 \frac{\text{mm}}{\text{cm}} = 510 \text{ mm}
$$
The answer is $\boxed{510 \text{ mm}}$.

$$
250 \text{ mm} \div 10 \frac{\text{mm}}{\text{cm}} = 25 \text{ cm}
$$
The answer is $\boxed{25 \text{ cm}}$.