Mental arithmetic - do you do it?

[arknor]

I would have crunched the numbers in my head to be honest, but with my day job I usually have to do this anyway. Calculators make you lazy, takes practice and discipline but it can be done easily with practice

windows + speech recognition + calculator = win just read it out loud

 

[Redz]

649.75 plus 1 plus 70.02 minus 1 is how I would have done it in my head.