When you are given the option of a new job whereby you are supposed to be paid 5000 $ per month with 1 day off in a week but your existing job is paying you 4500 $ with 2 days off in a week (without considering the other perks attached), you just don't go for the new job without considering your per day pay in both the cases. And since your existing job is paying you more per day pay (204 ) as compared to your new one (192 ), you don't consider moving. This explains the mathematical way of thinking is somewhat the consideration of opportunity cost for any outcome.
Mathematical way of think is never a natural attribute, but it is learned one. Over your life time you keep learning and you keep employing various mathematical ways of going about any thing.
Consider yourself entering a shoe shop. You notice the price tags on various shoes. Your unconscious mind keeps making notes of the various prices. You roam around for a while and after that you leave the shop with a deep tagging of prices on your mind. Later on, you recall one of the price tags quoting 9.99$.
Your unconscious mind considers the price to be 9. You know that the price was 9.99 and not 9, but somehow the not-so-mathematical corner of your mind keeps missing the extra 0.99. But only if can realize that the price was set to make you think that it is actually costing you 9 and not 10, is when you can mathematically rationalize the real cost.
Next time when you enter the same shop your mind will round off the price to help you make a mathematical decision. Now you will consider paying 10 for 9 or 100 for 99. This will help you consider the other choices as well.