Finding the Digital Roots by Casting “9”
What is Digital root?
If we add up the digits of a number until there is only one number left we have found what is called the digital root. In other words, the sum of the digits of a number is called its digital root.
Example:
For 5674, 5 + 6 + 7 + 4 = 22 and 2 + 2 = 4
» 4 is the digital root of 5674
One use of digital roots is for divisibility tests (like 3 and 9). This method makes it easier to calculate the digital root.
Example:
Find the digital root of 257520643
Steps:
1. 2 + 7 = 9, cross out 2 and 7.
2.4 + 3 = 9, cross out 4, 3 and 2.
3.There are no other groups of numbers adding up to 9.
4.Add up the remaining digits, 5 + 5 + 0 + 3 = 13.
5.13 is more than 9, so 1 + 3 = 4.
6.The digital root is 4.
If there is nothing left after having cast out nines then the digital root is 9.
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