People take the opportunity to do most of their Christmas shopping the day after Thanksgiving Day, which the media and retailers call "Black Friday, since almost everything on sale have considerable discounts. People arrive way before the stores are open, waiting in line for hours to be the first ones buying the best or most popular items at bargain prices and before it sold out. My wife was one of those early shoppers, leaving at 4 a.m. to the mall.

During Black Friday, people should be very careful not being tricked when purchasing items they may think are at bargain prices. The shopping hype or frenzy of such day could easily distract people for using their critical thinking skills or skepticism when something looks too good to be true. This is exactly what happened with my wife when she tried to buy a nice golf shirt as my Christmas gift.

The regular price of the golf shirt was $32 but with a 25% discount, which my wife thought to be good deal even though she did not know the exact amount she was going to pay for the golf shirt.

Like many people, my wife had always questioned the reasons for learning mathematics other than the basics, even though she did fairly well in math courses during her schooling years and college. She was one of those students who did not see any practical reasons for learning advance math topics, such as Algebra, Geometry, Statistics, etc. since she was not going to be a scientist, engineer, or any career that involves mathematics. My wife was one of those students who believed that Algebra made simple problems too complicated. In summary, she was not fully aware of the usefulness of learning mathematics for her daily life activities.

However, it was the experience she gained in the mathematics courses that helped her develop the ability to make sense of numbers. And it was this ability that helped her decide not buying my Christmas gift when the cashier notified it was $30 for the purchase. Probably, many people would have paid the $30 for the golf shirt due to their excitment of being part of big event such as Black Friday, in which the belief is that all purchases are the best bargains. Fortunately, my wife did not get caught in the hype of Black Friday and she questioned the purchasing amount for the golf shirt. The cashier explained the purchase amount was a good bargain even after the discount and sales tax were applied to the purchase.

For a few seconds, my wife hesitated to follow her common sense or number sense since after all, she wanted to give me a gift. However, she told the cashier to cancel the purchase since she was convinced the purchase amount was too high for an item that was a 25% off and a sales tax of 7%. In the way back home, my wife was regretting her decision for not buying my gift. When she got home, she immediately asked me if her decision was correct or not since she did not remember how to calculate the discount of 25% and the sales tax of 7%. I showed her the computations: 25% of $32 is $8, so the sale price should have been $24. The sales tax of $24 is $1.68 (7% of 24), so the purchase amount should have been $25.68. My wife felt relief about her decision! My wife's common sense about numbers was something she developed from taking math courses. A great benefit indeed for learning mathematics!