DAMN. So I am not an expert at remembering my own puzzles... I meant to say that you have tables for 7... But you DID get it.
Woo Hoo, well at least your honest. 1 out of 2 isn't too bad. Tell me when your ready to learn to square 2 digit numbers in your head, or at least the 90's (really easy). Pugs
I am also an expert at finding "mistakes" in posts as in spelling, grammar, or people writing the words "their" instead of "they're" or "your" instead of "you're"... I am ready NOW, PUGS I can do 99 * 99 really fast, and multiply really fast... but I don't know what you mean about "square 2 digit numbers"... is that the same as x square where x is any integer of the set 0-99 ? (x) square | {0...99} ?
Your right, 99*99 is the same as 99 squared. How fast can you do them in your head? Using the way I do it, you can do the 90's in a few seconds. If it's lower then it's a little harder because you have to use a different method. Now do 96 squared in your head. Pugs
WAAAAAAAAAAAAAAAAAAAA!!!!!!! I can't. 99 * 99 is the same as (100-1)(100-1) and when you do (x-y)(x-y) that's the same as (x*x)-2xy+(y*y)... so I can do that fast and get that 96*96 is (100-4)(100-4), or 10000-2(400)+36... or in other words, 10000-800+36, which equals 9236... is that right? Whats YOUR secret? SHARE. I shared my x-y square method. You should learn to differentiate "you're" and "your" spellings... it will help you (I told you I was an expert)...
Wrong! YOUR answer is wrong, but YOU'RE going in the right direction. 100-96=4 96-4=92 4*4=16 96*96=9216 Now you try 95 the same way. Pugs EDIT* I guess I shoud explain it. You do the following: 1) 100 minus the number, in this case 96, to get 4. 2) Remember that number! Take your original number, 96, and subtract the number you got from that, so 96-4, which is 92. 3) 92! That is the first part of your answer. 4) Now take that number I told you to remember, do you remember it? Good, square that number, so 4*4, which is 16. 5) 16! that is the last part of your answer. 6) Your answer is 9216! Piece of cake.
CRAP. I did 6*6 instead of 4*4... I'm a CARELESS expert. 95*95 = 9025? [crossing fingers] [double-checking on Start-Run-Calc[Enter]...] YESS!!!! HOLEY MOLEY. You're GOOD! I just took Math for Elementary School Teachers, and I wanted to share with you guys all the methods for finding if a HUGE number is divisible by any single digit. Example: is 183 a prime number? By the same token, is 187 a prime number? What about 57? If anyone cares to use some valuable time, would you like to know how to find out if a number is divisible by all of the single digits? Is it divisible by 2,3,4,5,6,7,8,9,or 11?
Nicely done! I think we're the only ones posting, but other people are defiitely looking. I saw the count go from 1813 to 1819 after I made my last post to now. Are you ready to learn how to do all of the other 2 digit numbers, or are you going to give your lesson now? Pugs
You guys are nothing. I met the son of a client who could do 3-digit multiplication in his head, i.e. 234 X 489. He could do it faster in his head than I could on a calculator. It was an amazing feat...
Yeah I've read about people doing things like that. I'm sure their IQ's are also light years ahead of mine. Pugs
PUGS, do the other ones... while I tell you this one... Does he have a JOB, 2 kids, a wife, and ClutchBBS threads to worry about? I DON'T THINK SO. Anyway, to find out if a number is divisible by: 2, last digit is even 3, all digits add to 3,6, or 9 4, last 2 digits divisible by 4 5, last 2 digits either 5 or 0 6, divisible by 3 AND 2 7, [I forgot... or maybe I didn't learn it, EDIT- but this guy has it down... ] 8, last 3 digits divisible by 8 9, all digits add up to 9 10, you better know this one... 11, add alternating digits. Subtract first and second alternating totals, if number is divisible by 11, NUMBER is divisible by 11. Example, 20933 (2+9+3)-(3) = 11, so 20911 is divisible by 11.
It looks like I have some studying to do..... If you want to square the other numbers here is the trick, like I said earlier, it's a little harder: Lets use 67. 1) Think of the closest number to 67 that ends with 0, in this case 70. 2) Ask yourself what you did to 67 to get to 70, you added 3. Now you have to do the opposite of that to 67 to get your next number. So instead of adding 3 you'll subtract 3, to get 64. 3) Now your 2 numbers are 64 and 70. Here is the hard part. Think of 64 as (60)+(4). Your going to multiply both of those numbers by 70 and add them together. 4) 60*70 is easy, you get 42 then add the 2 0's to the end to get 4200. 5) 4*70 is easy as well, 4*7 is 28, then add the 0 to get 280. 6) If you haven't forgotten your numbers now you add them together, 4200+280=4480. That's not your answer. 7) Go back to the first steps, what number did you add and subract to your original number? It was 3, so you have to square this number and add it to your total. 8) 4480+(3*3)=4489 <----That's your answer So to put it in number form: 70-67=3 67-3=64 6*7=42, add the 0's from 60 and 70, to get 4200 4*7=28, add the 0 from 70, to get 280 4200+280=4480 3*3=9 4480+9=4489 Just a little harder. Ok your number is 74, go for it! Pugs
