take aways

On Wensday in my math´s group Mr Gunn gave us a follow up.Our follow up was take aways.If you don´t no what take aways are they are like when you are doing adding but instead of doing the pluce sine you do a line across like this  - heres an exple 10-1=9.It = nine because you have 1o and then you take away on of the numbers in the lot and it leaves you with nine.And thats how you do take aways.