Quick - you have two seconds to answer this question, and you have to do the math in your head:
(And no. You don’t get to cheat by looking ahead at any other posts. )
What is 8% of 25?
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
Here’s another math question. Again–two seconds, in your head.
(If you’re like me, this is a lot easier than the first question.)
.
What is 25% of 8?
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
The answer is the same. Percentages are interchangeable, you see? 25% of 8 is the same as 8% of 25.
When you think about it, this makes perfect sense. You multiply 25 times 8 (or 8 times 25, whichever you prefer), then move the decimal twice. But it’s easier on your brain to do “25% of 8” than “8% of 25”.
Thank you, random Facebook meme, for teaching me this on the last day of 2020!
lol interesting…
Interestingly, as soon as I saw the problem, I thought of it as 25% of 8.
With practice, such shortcuts can become habits.
More generally, multiplication is commutative and associative.
I know: duh, right?
What is difficult about this or 8% of 25 that cannot be solved in seconds? Pretty easy question. How did you graduate elementary school? 
Were you able to calculate 8% of 25 in your head in a matter of seconds?
If so, good for you. I am as proud of you as your mother. You, sir, are a first-rate genius.
Yes, and I bet all my friends can do so. Why is it so difficult?
Divide 25 by 100, 25 cents. Multiple 25 by 8 and it is 200 cents. It is that simple. (Or you can multiply 25 by 8 and found 200 and divide it by 100. Same thing)
I could this calculation since I was in 4th grade. And almost all of my friends did, too. lol