Am I missing the obvious ?

[Scouts]

Tom is wrapping presents and has to cut a roll of ribbon into one metre lengths.If it takes him 2 secs to measure and cut one length how long will it take him to do the whole roll ?
Don't you have to know the length of the roll?

[Aquagility]

Yes. The answer will be 2(L-1).

[Dave G]

I'm also dim
how does that work
regards dave

[Aquagility]

Each metre length takes 2 secs, but the last metre is left over and does not need cutting.

[GlenB]

But the last length still has to be measured