For iPad or iPhone or iPod in school hours: Skype
For other times: Skype or a gadget to add, subtract or do any maths thing without you having to think.
I prefer the former.
Girl 1: Stop Skyping
me! I am doing maths!
Girl 2: On your 'calculator' on your iPad, huh?
Girl 1: Yeah. I am. haha ;)
Girl 2: You are skyping your maths