Message Font: Serif | Sans-Serif
 
UnThreaded | Threaded | Whole Thread (21) | Ignore Thread Prev Thread | Prev | Next | Next Thread
Author: Goofyhoofy Big funky green star, 20000 posts Top Favorite Fools Top Recommended Fools Feste Award Nominee! Old School Fool Add to my Favorite Fools Ignore this person (you won't see their posts anymore) Number: of 19774  
Subject: Re: What is 47X63? Date: 2/11/2013 8:58 PM
Post New | Post Reply | Reply Later | Create Poll . Report this Post | Recommend it!
Recommendations: 5
47x63 in your head is not hard if you learn "speed math." I used to do this all the time, it's like a parlor trick. Yes, you need to be comfortable with numbers, but if you are, it's simple. I read a "speed math" book when I was a teenager, I don't remember the title, but it showed how to do all sorts of tricks with numbers. For instance:

Instead of 47x63, you multiple 50 x 60. 3000, right? You get the 50 is close to 47 and the 60 is close to the 63, capice? Easy so far.

Now you multiplied too much, so 3 (that's the 50 minus the 47) times 63 is 189. (You can do 3x60=180 then 3x3=9 to get there if you need to.)

Remember all the way, one whole step ago, to the first 3000? OK. Subtract 189 from 3000. Actually, subtract 190 from 3000 = 2810, then add the 1 extra to get to 189, it's 2811. If the "190" flummoxes you, you could subtract 200, then add back 10, then add 1.

But you didn't multiple by 63, you multiplied by 60 way up top, so you have to add another 3x50 (not the 47, because you already accounted for that in the first step.)

2811 + 100 = 2911 + 50 = 2961.

I know it sounds complicated, but when you learn to break down the processes and do it - and get comfortable with it - you can amaze your friends. It will not help you get girls, however.

I used to be able to beat someone with a calculator, but only if I made someone name the two numbers and then start mentally - while the other person began typing the digits into the keyboard. Of course my brain was more active then, now I'd have to stumble through it.

Anyway, the moral of the story is: find the big, basic parts. Break the problem down. Add up the pieces. Announce the answer. It's sort of like life, only with numbers.
 
Post New | Post Reply | Reply Later | Create Poll . Report this Post | Recommend it!
Print the post  
UnThreaded | Threaded | Whole Thread (21) | Ignore Thread Prev Thread | Prev | Next | Next Thread

Announcements

Post of the Day:
Apple

Apple and Ninety Years Ago
What was Your Dumbest Investment?
Share it with us -- and learn from others' stories of flubs.
When Life Gives You Lemons
We all have had hardships and made poor decisions. The important thing is how we respond and grow. Read the story of a Fool who started from nothing, and looks to gain everything.
Community Home
Speak Your Mind, Start Your Blog, Rate Your Stocks

Community Team Fools - who are those TMF's?
Contact Us
Contact Customer Service and other Fool departments here.
Work for Fools?
Winner of the Washingtonian great places to work, and "#1 Media Company to Work For" (BusinessInsider 2011)! Have access to all of TMF's online and email products for FREE, and be paid for your contributions to TMF! Click the link and start your Fool career.
Advertisement