I have a question about the meaning of mental math...
What exactly is considered mental math in a case interview?
Can looking at numbers, separating them into easier to calculate numbers and noting down the bits and pieces on paper so you don't forget and then adding them all up in your head pass for mental math?
I am asking cause I wonder if I am expected to keep all the strings I separate in my head and not write them down at all and recall them smoothly and only write the final digits down.