# Math - Single Digit Sum

## What does Single Digit Sum mean?

Any number (say 3456) to be equated to a single digit sum, we just add all the digits together (3+4+5+6 = 18) until they become a single digit (1+8=9). i.e. less than 10

This article explains a shortcut method to find the single sum for any number through a simple mind math.

# The magic number 9

The shortcut method is that you can skip all the 9’s from the digits, also by excluding all the numbers that adds up to 9.

For example: 12789, Single Sum = (Skipping the digit 9) 1+2+7+8 => (because 1+8 is 9, skipping the digits 1 & 8) 2+7 => 9

Technique: Adding any number to 9 will result in a single sum of the added number.

9+3 = 3,

9+24 = 6,

9+9999 = 9,

and likewise.

## If there are no easy 9's

If there are no numbers that easily adds up to 9 at a single glance (say 786), then start the manipulation by considering the number closest to 9 (number 8 in this case). Then to make it a 9 how much ever is the difference, subract that difference from the other digits and eventually make the calculation simpler (7+6-1 because 9-1=8), until you arrive at smaller numbers (-2+6-1 because 9-2=7) and ultimately the single sum (6–2–1=3).

So, 8 means subtract 1 from any other number, 7 means subtract 2 from any other number and so on.

## Practise

As you practise this technique well, finding the single sum for even large numbers will look easy. Just be well versed with the numbers that adds to 9. i.e. 5+4, 6+3, 8+1, 7+2.

543=?

9321=?

12345=?

201305=?

9690194889=?

Kindly let me know if the article needs correction / improvement. TIA.

learner. seeker.