Thread: Understanding Units

Please advise if you can

I have one litre of liquid, this is equal to 1000 ml. I want to add 25% more liquid to the original volume.

I say 25% / 100 x 1000 = 250 ml. I then add this to the original 1000 ml to give 1250 ml, then I say; 1250 ml / 1000 ml = 1.25 L

The maths looks good, but the problem for me is in the units, you see if ml / ml is cancelled out, then I know its a fluid, but where does the L litre come from if I have cancelled the units out?

I thought that would leave unity?

David

Originally Posted by David Green

Please advise if you can

I have one litre of liquid, this is equal to 1000 ml. I want to add 25% more liquid to the original volume.

I say 25% / 100 x 1000 = 250 ml. I then add this to the original 1000 ml to give 1250 ml, then I say; 1250 ml / 1000 ml = 1.25 L

The maths looks good, but the problem for me is in the units, you see if ml / ml is cancelled out, then I know its a fluid, but where does the L litre come from if I have cancelled the units out?

I thought that would leave unity?

David

You must take care with your unit fractions what you really have is



So when you multiply by this fraction the mL reduce out, but the L stays in the numerator.

This gives