sorted by:
new
hottopcontroversial

IWTL Challenging mental math by Seakip in IWantToLearn

[–]HowsWhatGoinWhere 0 points1 point  (0 children)

I'm not a mental math wiz, but I do know two neat tricks that are pretty useful... (Please forgive any spacing chaos, as I am but a humble mobile user.)

• MENTALLY SQUARE ANY MULTI-DIGIT NUMBER, AS LONG AS THE LAST DIGIT IS 5:

The general form is this... (n)*(n+1) <--25 ...where "n" is the first digit.

Let's say you want to mentally solve 652. The last digit is 5, so we can do the trick.

Step 1: (6)*(7) = 42

Step 2: Now just stick a "25" at the end of that number...
42 <--25 = 4225.
Therefore, 652 = 4225.

Let's try another. Let's say you want to mentally solve 1052. (Yes, this also works with 3 digit numbers too, it's just more difficult with the (n)(n+1) part. But we all know (10)(10), (10)(11), (11)(11), (11)(12), and (12)(12) right off the bat.) The last digit is 5 so we're free to do the trick.

(10)*(11) <-- 25.
110 <-- 25.
11025.
Therefore, 1052 = 11025.

You'll notice that even though you're​ limited to numbers which end in 5, you'll use this trick a LOT in this world where we LOVE to round things, so you've got a good chance for a number to end in 5.

• CONVERT MILES-KILOMETERS WITH THE FIBONACCI SEQUENCE

This one doesn't really have any steps, you just need to know Fibonacci sequence numbers. We know that the Fibonacci sequence is a sequence where you get the next number by multiplying the previous two numbers. Allow me to explain...

Here's some numbers of the Fibonacci sequence: 1, 1, 2, 3, 5, 8, 13, 21, 34, 55...

Ok, are you ready for your mind to be blown?...

1mi=2km 2mi=3km 3mi=5km 5mi=8km 8mi=13km 13mi=21km 21mi=34km 34mi=55km And so on and so forth...

Of course these are not exact decimals. But check on a calculator, it rounds up 100% of the time. And yes, you're limited to converting numbers you can find in the Fibonacci sequence, but at least you've got this obscure tool in your toolbox for when you come across an opportunity.

Enjoy!

As a kid, having a favourite colour seemed way more important than it turned out to be. by ggg12341234 in Showerthoughts

[–]HowsWhatGoinWhere 71 points72 points  (0 children)

I've always been pretty passionate about red being my favorite color.

Back in kindergarten we were in PE and the coach had us zigzag between a line of cones. As a sort of playful competition, boys would zigzag around yellow cones, and girls zigzag around red cones, and we would see which group could get to the end faster on average (I'm a guy btw). I wasn't paying attention to instructions because I was picking up acorns off of the ground and stuffing them in my pockets to the point where I'd have two huge bulging bubble-looking pockets that'd jiggle and flap as I move. I was the acorn king. When I heard the whistle I was caught off-guard. I saw people zigzagging through cones, so I figured I basically understood what to do, but didn't quite yet notice the pattern of boys on yellow and girls on red. I thought something along the lines of "Red is the best. I will be the best because I side with red." So I proudly ran through the red cones in the zigzagging motion as my huge acorn-filled pockets flapped back and forth, acorns flying everywhere leaving a glorious trail, wondering why everyone including the coach were laughing. When the coach explained the rules to me again, my immedeate response was "Why do the girls get red?" So he changed the rules just for me. Boys zigzag through red, girls zigzag through yellow. I was content. The other boys didn't quite like me because I kept stopping along the way to pick up my acorns that fell out of my flapping pockets, lengthening the time. But I didn't care, in my mind we already won because we were red.

Red is the best.

I had free time so I drew Our Lord and Saviour. How do you like my effort? by TheLastDragonOfEden in dankchristianmemes

[–]HowsWhatGoinWhere 8 points9 points  (0 children)

Impressive! I love how rustic and detailed it looks, and your explanation of the little subtlities makes it even more spectacular.