The metal bar is 93 cm 3 mm long. A piece 85 cm 6 mm long is cut off. What is the length of the metal bar remaining? A square window is made from 4 metal bars, each 200 cm 6 mm long. What is the perim

We know that $1 \text{ cm} = 10 \text{ mm}$.

$$93 \text{ cm } 3 \text{ mm} = (93 \times 10) \text{ mm} + 3 \text{ mm}$$ $$= 930 \text{ mm} + 3 \text{ mm}$$ $$= 933 \text{ mm}$$

$$85 \text{ cm } 6 \text{ mm} = (85 \times 10) \text{ mm} + 6 \text{ mm}$$ $$= 850 \text{ mm} + 6 \text{ mm}$$ $$= 856 \text{ mm}$$

$$\text{Length remaining} = 933 \text{ mm} - 856 \text{ mm}$$ $$= 77 \text{ mm}$$

$$77 \text{ mm} = 70 \text{ mm} + 7 \text{ mm}$$ $$= (70 \div 10) \text{ cm} + 7 \text{ mm}$$ $$= 7 \text{ cm } 7 \text{ mm}$$

The length of the metal bar remained was $\boxed{\text{7 cm 7 mm}}$.

6A. Perimeter of the window

$$200 \text{ cm } 6 \text{ mm} = (200 \times 10) \text{ mm} + 6 \text{ mm}$$ $$= 2000 \text{ mm} + 6 \text{ mm}$$ $$= 2006 \text{ mm}$$

A square window uses 4 equal metal bars, so its perimeter is 4 times the length of one bar.

$$\text{Perimeter} = 4 \times 2006 \text{ mm}$$ $$= 8024 \text{ mm}$$

$$8024 \text{ mm} = 8020 \text{ mm} + 4 \text{ mm}$$ $$= (8020 \div 10) \text{ cm} + 4 \text{ mm}$$ $$= 802 \text{ cm } 4 \text{ mm}$$

The perimeter of the window was $\boxed{\text{802 cm 4 mm}}$.