@phungcanhngo
Thanks Math Queen.You're awesome!
@paulcoonce2493
Good stuff. When in restaurants and I want to leave 20% tip, I move the decimal point then I double the amount. I have a lot of Nantradol in me too!
@markv00
Keep up the great explanations! I appreciate it when you slow down a bit, so we can absorb what you just did. I keep saying, you not skipping steps in your explanations is so great. Some instructors will perform a step where a number is changed and don't explain why "415 is now 86", (just made-up numbers as an example), and it shows off understanding the rest of what they're explaining. Thanks for you work!
@Megaexplosionman
I didn't know about the switching mechanic or the fraction stuff! What I would do in the case of 19% of 50$ would be to calculate 10% twice and remove 1%: 0.1x50=5; 5x2=10; 0.01x50=0.5; 10-0.5=9.5.
@wesleyc.4937
Move the decimal LEFT two places; then multiply by percentage VALUE. -- 20% of 360 --> 3.60 x 20 = 72 (dollars) -- 18% of 400 --> 4.0 x 18 = 72 (meters) -- 4% of 7 --> 0.07 x 4 = 0.28 (kilograms) -- 107% of 1200 --> 12.0 x 107 = 1284 (dollars) -- 52% of 1250 --> 12.5 x 52 = 650 (meters)
@JamesStansell
107% of 1200 is just the base increased by 7% or 1200 + 7x12 because the hundreds cancel = 1200 + 84 = 1284
@MadMike-n5c
Thanks for the lesson!
@joopterwijn
Lol 😂62 and still learned something. Did the calculation different, no problem! But must say like the ‘decimal’ moving and last switch one!
@piggly-wiggly
The last tip was both blindingly obvious and something that even after decades of life had never dawned on me.
@lanehutchison9040
9.5 in my head in about 7 seconds or less. In my head I quickly figure out what 10 and 1 percent are. 10% of 50 is 5 and 1% is .5. 19% is the same as 10 and 9 1%s. 5+9x1.5= 5+4.5=9.5. Sounds and reads much harder than it is.
@Lynn-u7l
For 107% I just added 100% of 1200 to 7 times 12 which equals 1284
@Angi_Mathochist
Steps all can be done in my head: 20% of $360 (tip calculation) 20% is double 10% 10% of $360 is $36 2x$36 = $72 18% of 400m Trick: 18% of 400m = 400% of 18m 400% means x4 (x2 twice) 18x2 = 36m 36x2 = 72m 4% of 7 kg No tricks needed, small numbers 4x7=28 % means divide by 100 So = .28kg 107% of $1200 =1200% of $107 =12×$107 = 12x$100 + 12x$7 =$1200 + $84 =$1284 52% of 1250m 50% of 1250 + 2% of 1250 625m + 2500/100=25m = 650m 19% of $50 =50% of $19 =$9.50
@devondevon4366
Another trick in doing percentages is that n% of p = p% of n So, 16% of 25 = 25% of 16 a person might not be able to get the answer quickly when asked to solve 16% of 25, but quicker the other way around Let's show why 16% of 25 = 16/100 * 25/1 (16* 1/100) * 25/1 (16/1 ) * 25/100 So we got 25/100 , which is 25% as anything over 100 is the percentage 16 * 25% or 25% of 16. We know one quarter of 16 is 4 much easier than trying to find 16% of 25 another example 6% of 50 = 50% of 6 It may be easier to find 50% of 6, or half of 6 = 3, than finding 6% of 50 the reason of course is that n/100 * p can be written as n * 1/100 * p and 1/100 * p can become p/100 thus n/100 * p = p/100 * n . And when we see anything over 100, it is 'percentage' 2% of 100 = 100% of 2 This is easier as we know 2% of 100 = 2 But, also , 100% of 2 = 2
@JohnVanderbeck
I just break it down by 10% or 1% because anyone can do that math, it's just moving the decimal point. Then you just sum them up. 18% of 400 is just 10% of 400 (40) + 10% of 400 (40) - 1% of 400 (4) - 1% of 400 (4). 80 - 8 = 72.
@johannusarogvu3370
19% of 50: 20% of 50 is 10 and 1 % of 50 is 0,5, 10-0,5=9,5%
@전재영-t6e
아가[ 베이비] 나를 이해하려하지마라
@davepowder4020
Now there might be a problem with calculating in my head if I have different voices in my head coming up with different answers. 😛
@TRG972
For the last example, I took 1% of $50 = 0.50, then multiplied by 19 to get the $9.50. I like your way better though.
@scottholder4489
Dang...I wish she was my math teacher in HS or college...
@MathQueenSusanne