Question: describe how you can use a 30cm ruler to measure ribbon for each length?
Answer: You can use a 30 cm ruler to measure many lengths. Since 0.3 m = 30 cm, use ruler once. Use ruler three times to get 90 cm, then add another 15 cm to get 105 cm. Use ruler twice to get 60 cm, then add another 15 cm to get 75 cm or 750 mm.