2006-06-18 19:33:39 · 19 answers · asked by ridcully69 3 in Science & Mathematics ➔ Mathematics
9 is the magic figure of methematics
9x1=9
9x2=18 1+8=9
9x3=27 2+7=9
9x4=36 3+6=9
9x5=45 4+5=9
9x6=54 5+4=9
9x7=63 6+3=9
9x8=72 7+2=9
9x9=81 8+1+9
9x10=90 9+0=9
2006-06-18 19:47:51 · answer #1 · answered by yasin_17pk 1 · 3⤊ 1⤋
It's the largest single digit square of an integer
It's also the largest number that divides a number if and only if it divides the sum of its digits.
For all the people that keep saying some form of "if you multiply a number by 9 and then add it's digits, the sum equals 9" you are wrong. 11•9=99 and 9+9=18.
The actual result is what I wrote:
"9 divides a number if and only if 9 divides the sum of the digits"
9 divides 9+9=18.
This actually works for 1 and 3 also, but 9 is the largest such number. It is easy to see that it is the largest such number, because any number with more than 1 digit can not divide the sum of it's own digits (and thus it doesn't work).
2006-06-18 19:35:00 · answer #2 · answered by Eulercrosser 4 · 0⤊ 0⤋
The number 9 is very peculiar. If you add individual numbers at different dinominations in a number, and resulting number is substracted from this number, the resulting number is absolutely divisible by 9. Eg. 2456. 2+4+5+6=17. 2456-17=2439. This number 2439 is exactly could be divided by 9 with 0 as remainder.
Another utility of this 9 is in verifying the correctness of any calculator. If you want to check the reliability of a calculator, you feed 1/9, the screen should show 0.11111111111111111111. If it is so, your calculator is in good condition.
2006-06-18 20:41:06 · answer #3 · answered by K.J. Jeyabaskaran K 3 · 0⤊ 0⤋
Nothing Special, If you look at the figure 9 upside down It will look like 6 that's all.
2006-06-18 19:38:09 · answer #4 · answered by Bolan 6 · 0⤊ 0⤋
Take any number of any length (4,5 or 6 digits make a handy test), scramble the digits to make another number of the same length, subtract the smaller from the larger, and hey, presto! the sum of the digits in the answer is a multiple of 9.
2006-06-19 07:58:23 · answer #5 · answered by artleyb 4 · 0⤊ 0⤋
The multiples of nine (#9) all add up to the Number 9 (nine)
9 , 18 , 27 , 36 , 45 , 54 ,............108 ,.........162 ............*n
9 ,1+8=9 ,2+7=9, ................1+0+8=9,........1+6+2=9
2006-06-18 19:38:24 · answer #6 · answered by Basil P 4 · 0⤊ 0⤋
Largest single digit number in base 10, largest number modulo 10, if you multiply a number by 9 and add the digits, you get 9. It is an upside down six, but is not its inverse (unless we do modulo groups).
2006-06-18 23:21:02 · answer #7 · answered by kingpaulii 4 · 0⤊ 0⤋
I wasn't going to answer this question until I read Lumidee's answer.
9 is NOT the cube root of 3
it is the SQUARE of 3
9 is the cubed root of 729
9 is the age of my son - that's why its special to me.
2006-06-20 21:32:50 · answer #8 · answered by headcage 3 · 0⤊ 0⤋
9x9=81
81 mirror 18
1+8=9
9 mirror 9 :)
2006-06-19 22:58:14 · answer #9 · answered by fibonacci 2 · 0⤊ 0⤋
It is the largest single digit number.
It is square of 3.
It is one less than 10.
It is one more than 8.
2006-06-18 19:52:19 · answer #10 · answered by nayanmange 4 · 0⤊ 0⤋