How can you can use a 30 centimeter ruler to measure ribbon for each length 0.3 m?

First you convert 0.3m into 30cm because 0.3cm is out of 10dm then you start at the end of the ribbon and measure up to 30cm and mark that with your finger and there you go cut where you marked it and there is 30cm r if you have a better answer please help i dont know if this is good I'm only 10 Grade 5
Quite easily - 30cm is exactly the same measurement as 0.3 metres !