How much yarn is in that ball? A simple way to work it out!

I have lots of balls of yarn sitting around that I have partly used and have 

no idea how many meters are left.

This is what I worked out to do....

It's the maths teacher approach ( in a former life I was a maths teacher!!)

Here 10 meters of yarn = 12 grams

 Measure out ten meters from the ball, 

make a little ball around your hand, without breaking the yarn.

Measure the weight of the little ball on the kitchen scales.

Weight all the yarn.

This yarn is 60 grams.

I know that 12 grams is equal to 10 meters

I divide 12 ( the mass of 10 meters) into 60 ( the mass of all the yarn)

Which gives me 5, I have 5 lots of 10 meters
Therefor 5 multiplied by 10 is 50 meters of yarn.

Now isn't that easier than measuring it all....