Acmlm's Board - I2 Archive - Brain Teasers - Strange number facts
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beneficii
Posts: 185/567 |
RYJet11,
A silly trick: take any number from 1 to 9, times it by 3 then 37. what do you get?
pick any number btween 3 and 27. multiply it by 37 and you get a 3 digit answer. this number will obviously divide by 37 but the funny thing is that if you move the first digit of the asnwer to the end, or the end digit to the front the answer ALSO divides by 37
Don't the two above sorta go together? You could have omitted the first one.
Still, neat tricks! |
King_Killa
Posts: 23/117 |
I already know why it ends up like that. 
each row will get shifted over one when multiplying, and when you add up the rows their will be one more to each new column. |
Tanookirby
Posts: 157/509 |
Originally posted by Legault
I HAVE NO SQUARE ROOT KEY!!! damn you gateway keyboard.
Another way of typing the square root of a number is to calculate it to the 1/2 power
i.e.
n^(1/2) = square root of n
n^(1/3) = cube root of n
And here's another math trick I learned
11111111 * 11111111 = 12345678987654321
Try calculating that by hand, and you'll know why the answer ends up that way. |
Ikuzou
Posts: 54/181 |
I like this best:
i^i = 0.207879576
I understand e^i, but when it comes to i...
WT...F
I tried this on Google, and it managed to calculate it!
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Legault
Posts: 138/269 |
I don't find it on my keyboard....It should be right above the 6 but it isn't...There is nothing there. Well I still like that formula anyways.
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Ailure
Posts: 9995/11162 |
Uhm... if your talking about ^ it should be on every Keyboard. It is on all Swedish keyboard.
If you don't find it, then it's still there but just not defined on the keyboard.  |
Legault
Posts: 133/269 |
uh yeah. I like the quadratic equation.
-b+/-
I HAVE NO SQUARE ROOT KEY!!! damn you gateway keyboard. |
King_Killa
Posts: 5/117 |
Originally posted by Grey
I like the thought of perfect numbers...
Six, for example, can have all three of its factors added together to make itself. 1+2+3=6. The same goes for 28. 1+2+4+7+14=28.
hah, the thought of perfect numbers is nothing. The forumla to generate one is a lot more fun.
2^(n-1) * 2^n-1 = perfect if 2^n-1 = prime
I got bored and wrote a program to generate a large perfect number, I found on a website that 2^24036583-1 is prime, so if I plugged that number into my program, I would result with a perfect number.
I let it run all night and ended up with a 14,471,465 digit perfect number. |
Teundusia
Posts: 150/760 |
Originally posted by HyperHacker
A simple one I always found rather interesting:
2 + 2 = 4
2 * 2 = 4
2 ^ 2 = 4
Originally posted by RYjet911
to multiply the number 10 112 359 550 561 797 808 988 764 044 943 820 224 719 you just move the 9 at the end of the answer to the front
Multiply by what? 
Whoops sorry... to multiply 10 112 359 550 561 797 808 988 764 044 943 820 224 719 by 9 you just move the 9 at the end of the answer to the front |
HyperLamer
Posts: 3635/8210 |
A simple one I always found rather interesting:
2 + 2 = 4
2 * 2 = 4
2 ^ 2 = 4
Originally posted by RYjet911
to multiply the number 10 112 359 550 561 797 808 988 764 044 943 820 224 719 you just move the 9 at the end of the answer to the front
Multiply by what? |
Grey the Stampede
Posts: 1814/3770 |
Originally posted by NSNick
Originally posted by RYjet911
there are only two answers that make this phrase correct:
( )4+( )4+( )4=( )4
they are: (2,682,440)4+(15,365,639)4+(18,796,760)4=(20,615,673)4
and
(95,800)4+(217,519)4+(414,560)4=(422,481)4
You mean two integer answers.
Actually, there's 32 integer answers. 
Don't forget about your negatives becoming positives when they're evenly exponentiated. But they're still the same number, so I guess that's cheating... |
Teundusia
Posts: 145/760 |
well if you can find the decimal answers to these please feel free to post
these are perfect numbers: 6, 28, 496, 8128, 33,550,336
to find these out use this formula: 2n-1 X (2n-1)
To find the correct value for "n" you have to replace the N in this equation: (2N-1) so that the answer is a prime. replace the "n" in the first equation with the N in the second to find the perfect numbers.
Example with 2: 22-1=3
3 is prime
replacing 2 into this equation: 22-1 X (22-1) = 2 X (4-1) = 2 X 3 = 6
You can replace n with 2,3,5,7,11,13,17,19,31 and 61. They probably go much higher but there we go, the book only goes up to here with no other answers |
NSNick
Posts: 1872/3875 |
Originally posted by RYjet911
there are only two answers that make this phrase correct:
( )4+( )4+( )4=( )4
they are: (2,682,440)4+(15,365,639)4+(18,796,760)4=(20,615,673)4
and
(95,800)4+(217,519)4+(414,560)4=(422,481)4
You mean two integer answers. |
Grey the Stampede
Posts: 1812/3770 |
I like the thought of perfect numbers...
Six, for example, can have all three of its factors added together to make itself. 1+2+3=6. The same goes for 28. 1+2+4+7+14=28. |
tetsu
Posts: 2/6 |
wow. whoever thought of those had a lot of time on their hands |
KATW
Posts: 2640/3959 |
Divide any whole number less that 7 by 7, and you get a sequence that always repeats the numbers 714285 |
Smallhacker
Posts: 1343/2273 |
Originally posted by RYjet911
the number four is the only number in the english language to contain the same amount of letters as its value.
As far as I know, there's two of them in the swedish language.
Tre (Three)
Fyra (Four)
</uselessinfo |
Teundusia
Posts: 143/760 |
Here is a series of strange number facts... The first part is all about the number 37
A silly trick: take any number from 1 to 9, times it by 3 then 37. what do you get?
A sillier trick: take any number from 1 to 9 then multiply it by 3,7,11,13 and 37. what do you get?
pick any number btween 3 and 27. multiply it by 37 and you get a 3 digit answer. this number will obviously divide by 37 but the funny thing is that if you move the first digit of the asnwer to the end, or the end digit to the front the answer ALSO divides by 37
Pick any number, square the digits and add them. do it again and again and again. you'll either end up with 1 or a sequence which goes: 37,58,89,145,42,20,4,16,37
1/37=0.027027027027...
1/27=0.037037037037...
the number four is the only number in the english language to contain the same amount of letters as its value.
The number forty is the only number to have it letters in alphabetical order
two is the only number that gives the same number when multiplied by itself and added to itself
to multiply the number 10 112 359 550 561 797 808 988 764 044 943 820 224 719 you just move the 9 at the end of the answer to the front
526 315 789 473 684 210 multiplied by any number between 2 and 18 uses all the same digits in the same order, but starts at a different place (there is also an extra 0 at the end)
there are only two answers that make this phrase correct:
( )4+( )4+( )4=( )4
they are: (2,682,440)4+(15,365,639)4+(18,796,760)4=(20,615,673)4
and
(95,800)4+(217,519)4+(414,560)4=(422,481)4
8 is the only cube that is one less than a square
692=4761 and 963=328509. These two asnwers use all the digits from 0 to 9 between them. 69 is the only number that does this
153,370,371 and 407 have one thing in common. they are all "the sum of the cubes of their digits" in other words 153=13+33+53
There are 12,988,816 different ways to cover a chess board with 32 dominoes
if you multiply 21,978 by 4 it turns backwards
you can chop a lump of cheese into a maximum of 93 pieces with 8 straight cuts
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