Can you recommend a numeracy iphone application where you 'write' answers on the screen?

I'm trying to find a numeracy/maths/times-tables application for my children in which you have to 'write' the correct answer. There are lots of multiple-choice type times-tables applications but I'm looking for the equivalent of the various "Brain Academy" type applications available on Nintendo DS.

Age from 6 to 10.

Thanks for any help.

Unfortunately, the only app that contains everything you want so far seems to be MathBoard, which is iPad-only (it does however, look really well done). I didn't see anything for the iPhone that uses writing input rather than a number pad or buttons.