# Man reveals mind-boggling math trick and people regret not knowing it earlier

The world runs on hacks and tricks and it makes living so much easier. One of the areas that people delightfully and relievingly use hacks is in the field of math. To have some tricks to learn formulae or some incredible steps to get answers right is like a dream come true for many. It makes the problem-solving process less strenuous and adds to the subject's interest. Basic math is something we regularly use right from simple calculations to determining distances and lengths. A man, Ben Stephens on X, shared a mind-boggling hack to help people with the tricky dilemma of math. He shared the simplest method to find out the percentage of any number.

“Fascinating little life hack, for doing percentages- x% of y = y% of x,” he wrote in his post. He elaborated further, “If you need to work out 4% of 75 in your head, just flip it and do 75% of 4, which is easier.” While Stephens’ hack seemed interesting on paper, people paused their hopes to confirm whether the same was accurate and applicable in a real-life setting. Stephens gladly obliged and shared several daily life costs and percentage calculations to help. In a thread, he wrote, “If a jacket costs $50 but you can get it for 8% off, how much money do you save?” The answer would originally require a person to calculate 8% of 50 but using the trick, one can easily get 50% of 8 which is 4.

Sharing another example, Stephens wrote, “18% of 50 feels hard to calculate. But 50% of 18 is a doddle, right?” Right enough, using the trick Stephens suggested cuts down the mental effort required to get accurate calculations. While several people were impressed and stunned by his trick, @mcleish_t shared that the same comes from a much simpler and common mathematical analogy. He wrote, “Ah, the commutativity of multiplication- and how we hide it.” Stephens added to his comment, saying, “Turns out that pretty much everyone gets that 3 x 5 = 5 x 3, but that we have never thought (or been taught) to think of calculating a percentage as a multiplication operation.”

Fascinating little life hack, for doing percentages:

— Ben Stephens (@stephens_ben) March 3, 2019

x% of y = y% of x

So, for example, if you needed to work out 4% of 75 in your head, just flip it and and do 75% of 4, which is easier.

In another thread, he added, “A lot of people (including grown-ass adults working in STEM fields) have never really made the connection and seen percentage calculation as a multiplication function.” Stephens even clarified several doubts people had about the trick and highlighted that it’s more simpler and quicker to understand than it seems. He also shared that the hack can successfully work with any two numbers. However, like every theory, there are limitations here as well. Stephens pointed out, “The trick is only really useful if one of the numbers is convenient. There are plenty of cases where you're probably gonna have to bust out the calculator.”

Yep! Turns out that pretty much everyone gets that 3 x 5 = 5 x 3, but that we have never thought (or been taught) to think of calculating a percentage as a multiplication operation.

— Ben Stephens (@stephens_ben) March 5, 2019

Broadly speaking, the trick is only really useful if one of the numbers is convenient. The 14% of 88 example is a pretty good illustration of the fact that there are plenty of cases where you're probably gonna have to bust out the calculator.

— Ben Stephens (@stephens_ben) March 11, 2019

People applauded the man for sharing a life and time-saving hack. @dalefraser wrote, “I was just thinking great but it doesn't work if it’s like 100, like 10% of 100 isn't 100% of 10, oh shit it is, mind blown!” @1Batmom added, “Ben wins the internet!!” @MathsNotts exclaimed, “I teach Math at the primary level and had never realized this. 50% blown away| 50% going DOH!”

Who knew multiplication is commutative :) We really need to improve maths education!

— Tim Cropley (@Fe_tj) March 5, 2019

How could maths teachers let us live without this!

— Lom Harshni Chauhan (@lomharshni) March 5, 2019