Percentages Shortcuts

An easy way to get some percentages that at least one of them end in "0" is to multiply a couple of numbers.

For example: 20% of 50=? Simply multiply 2x5 and the answer is 10.

70% of 90=63, 80% of 50=40, 20% of 70=14

Lets try this equation: 9% of 50. When dealing with single digit percentages you only need to multiply and stick a decimal in between your answer. In this case the answer is: 4.5

7% of 90= 7x9 (63) Answer: 6.3
3% of 70= 2.1
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So what if it gets a little more complicated? As long as one of the numbers end with zero (0) then this formula will work. Notice though, you never use the “0” to multiply.

How about 71% of 50? Just multiply the 7x5, put a decimal, then multiply 1x5. The answer: 35.5
How about 20% of 14? 2x1 decimal 2x4 = 2.8
30% of 11=3.3
20% of 31= 6.2

When the multiplication comes out a double digit number you just have 1 simple step to add.

Let’s try 89% of 50=? 8x5=40 decimal 9x5=45. Just add the “4” in the “45” to the “40” and leave the “5” in place. Answer: 44.5.
72% of 80= 57.6
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Another one I figured out that works every time is when both numbers end with a “1”

You do the almost the same as with the percentages ending in “0” but you need to also do some adding. All answers end with a “1”.

Example: 41% of 21=? Multiply the 4x2 (8) (.) add 4+2 (6). “1” on the end. Answer: 8.61
71% of 11= 7x1 and 7+1 = 7.81
31% of 61=3x6 and 3+6 = 18.91

When you multiply or add and you get a 2 digit number you just add the number ahead, just like the percentages with “0”.

Example: 81% of 51=? 8x5 (40) and 8+5 (13). Add the “1” in the “13” to the “40” put your decimal and then put your “3” and add the “1” on the end. Answer: 41.31
91% of 81 = 72+17 = 73.71
61% of 51 = 30+11 = 31.11
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Changing the percent sign (%) to the other number will come out to the same answer. Sometimes it is easier to do it that way. It works for all percentages.

Example: 44% of 50 is the same as 50% of 44. The 2nd problem is much easier to figure out and both answers are “22”.
33% of 11 and 11% of 33 both come out to 3.63
98% of 23 and 23% of 98 both come out to 22.54

Photo: Pixabay - Artist: thehaladesign

Howdy y’all. It’s me, ninong7 aka UJ aka John. Just a short intro about myself. I am a Texan that has retired in the Philippines. I moved to the Philippines with my wife back in May 2010. I am retired from the US Air Force. The music I like is mostly Classic Country and Classic Rock. I guess you could say that I am “Classic”. I play dominoes when I can find someone that will play, I play chess, cribbage, spades, hearts, Empire Builder, Rail Baron, Acquire and a few other games. I like to write poems and stories (although pretty novice) and I love learning about history, just about any history. I’m at home on my computer a lot but if I could afford to, I’d be traveling and documenting my travels to post in my blog. I hope to get to know a lot of you through PeakD and Discord.