Calculus or algebra? Or are you stuck down there with the accountants?
How to calculate faster and better??

Eat lots of almond and sea food, drink code lever oil, sleep a lot, that's it I guess, more or less... :))

Yep, practice helps.
To calculate faster, practice 100 2-3 move combos a day. I can do 100 Shredder puzzles in less than 20 minutes. Think of it as the chessic equivalent of going for a morning jog.
To calculate more accurately, try working on pawn endings without moving the pieces. There are relatively few legal moves to consider, so it's possible to solve most pawn endings with just a bit of patience.
Take 20 minutes, analyse the pawn ending as completely as possible, then write down every variation. Then check your answers with the solution. Give yourself full marks only if you saw every move of the solution.

Eat lots of almond and sea food, drink code lever oil, sleep a lot, that's it I guess, more or less... :))
You over-estimate the benefits of healthy food. Sleeping well does help though.
Can someone please help me with calculation.