Please can someone explain how this works? My child has an example from school but the line starts with the lower number and ends in the highest number.
In my mind, you have the higher number at the start then add your lower number on.
I think I am totally getting the wrong end of the stick with this and my child has helpfully forgotten everything they had learned before half term 
I have tried googling but I think I am confusing myself even more.
Back to school tomorrow and wishing I had asked this question last week when I first looked!
Any help gratefully received. 