When I do calculations I use excel. I keep calculating figures several times. And I know I am prone to make mistakes. Bur somehow I keep make it one or two blunder mistakes towards the end. Perhaps I was super exhausted from intense work, but it was a ridiculous mistake. I was told if CPA in India makes such a mistake, his or her license is pulled. I feel very bad that when I try to focus, I still make mistakes. How do I fix myself? Is there a special meditation I can try, or do I need to meditate more?