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....

Keeping the doona in the cover!

Here is my latest idea. My doonas are always getting scrunched up in the covers.
My solution is to use my snap press. I put snaps into each corner of the doona. Then the sockets of the snaps into the inside corners of the doona covers, I put them in the seam allowance so the snaps would be hidden.
Now snap the doona to the cover and turn the right way! Simple. Now off to test if it works. I may end up adding a couple more snaps in the side seams if the doona is still bunching.

I'm using my iPhone to post this. My first attempt of an iPhone post!