Can anyone give me the 'Rule of nines'?

Question

By which you can check all the big multiplication of numbers without doing the real multiplication

It is used for checking multiplication.It is not to find mutiples of 9.

Answer 1

The "rule of nines" is a method to determine if a number of any length is evenly divisible by 9. Simply add all of the digits of the number, and if the sum is also evenly divisible by 9, then the original number was evenly divisible by 9. If the sum is still a very large number, simply repeat the process of adding up the digits until you reach a number small enough to easily determine if it is a multiple of 9.

As an example: Is 143,468,325 evenly divisible by 9? Add the digits to obtain 36, which is divisible by 9, so yes the original number is as well. Or we can add the digits of 36, which equals 9 and it is quite obviously evenly divisible by 9. ^.^

Answer 2

Checking the mutiplication of any number by 9:
Add up all the individual digits of that number & then add up the digits of the sum & go on like this till you get the final sum in one or two digits. If the so arrived number is a multiple of 8, the original number is perfectly divisible by 9. If not, the original number is not divisible by 9.



Here is an example:

Take a random number 987654308974653654387

Sum of the digits =117

Sum of 1+1+7 = 9 (Which is perfectly divisible by 9 without leaving any remainder)

So the random number taken is divisible by 9.

So easy & simple.

(The same rule can be applied to test whether a number is perfectly divisible by 3. If & only if the summation of digits (so obtained as in the case of division by 9) is perfectly divisible by 3, the number taken for divisibility is perefctly divisible by 3.

Answer 3

total up all the digits of the number and then check whether it is divisible by 9. if tht 2 is a big no. keep on adding until u get a suitable number.
for eg: 223456767867
2+2+3+4+5+6+7+6+7+8+6+7=63
now is 63 divisible by 7? yes or if u want to find it out whether it is divisible or not then add
6+3=9
is 9 divisible by 9? yes
so 223456767867 is divisible by 9.
theres no method for 7 and for 8 you have to check the last 3 digits of the number. if they are divisible by 8, then the whole no. is

Answer 4

Rule of Nines demonstrates a simple mathematical rule . You can take any positive whole number with at least two digits, and with a few manipulations, the end result is always nine!
So how does it work? There are two parts to the rule:
Part One: If you find the sum of the digits of any whole number (larger than nine) and subtract that sum from the original number, the result will always be a multiple of nine.
Part Two: Every multiple of nine's digits will add up to nine (or another multiple of nine, who's digits will add up to nine, etc.) In other words, no matter what number you begin with, the end result will always be nine!

Answer 5

If the sum of the digits of a number is exactly divisible be 3 or 9 then the number is exactly divisible by 3 or 9.

Answer 6

What you are looking for is usually called "casting out nines". First, you can "reduce" any decimal number n to a single digit d(n) as follows:

- if n=9, d(n) = 0;
- if n is a single digit number other than 9, d(n) = n;
- if n has more than one digit, d(n) = d(sum of the digits of n)

(d(n) is just n mod 9)

To check a multiplication x*y=z for any single digit error, calculate d(d(x)*d(y)) and check that it is equal to d(z). (The same trick works for other arithmetic operations.) A similar trick works by calculating mod 3.

You can find more information by Googling "casting out nines".

Answer 7

easy.
if you want to know if an integer is divisible by 9, you sum up all its digits:
16 is divisible by nine? no, 1+6 = 7, and that is not divisible.
598 is divisible by nine? no, 5+9+8 is 16, 7 not divisible
594 is divisible by nine? yes, 5+9+4 is 18, 9 OK!!!

Answer 8

multiply 9x1=9 / 9x 2=18 / 9x3=27 / 9x4=36 and so on
when you add the answers together, they add up to 9
1+8=9 / 2+7=9 / 3+6=9 and so on...
I don't know if that is the rule of nines, but it is weird about nines...

Answer 9

Take any no. if its last digit is even no., then it is dividable by 2. If its sum is dividable by 3,6 or 9 then it is dividable by 3. If the last digit is 0 or 5 then it is dividable by 5. If the figure of last two digits is dividable by 4 then it dividable by 4. If the sum is dividable by 2and 3 then it dividable by 6. If its sum is dividable by 9 then it is dividable by 9. For 7 and 8 what to do, I fergot.

Answer 10

Several factors are used to determine the severity of a burn injury, including the patient's age, size and depth of burn, and the location of the burn. A "Rule of Nines" chart is used to determine the total body surface area (TBSA) that has been burned. The chart divides the body into sections that represent 9 percent of the body surface area. In determining the TBSA of children and infants the Lund-Browder chart is used. A separate chart is used because the surface area of the head and neck of children is larger and the limbs are smaller than adults.