Check subtraction using Digital Roots

In my previous post, we learnt about checking addition sums using digital root.

Now we will learn checking subtraction sums using digital root.

REMEMBER

The digital root of a difference is the difference of the digital roots

of the numbers in the subtraction.

We will understand this concept by taking two cases:-

Case I--- When digital root of greater number is greater then the digital root of lesser no. In this case we get positive digital root.

Case II--- When the digital root of greater no. is lesser than the digital root of lesser number. In this case we get negative digital root.

Case I

1. Subtract two numbers 872 - 411.

2. Digital root of 872 is 8

3. Digital root of 411 is 6

4. Now subtract 8-6 is 2.

This implies that Digital root of 872 - 411 will also be 2. Let's verify.

5. Subtract 872 - 411 = 461

6. Digital root of 461 is4+6+1=11 again 1+1 = 2.

Hence the digital root of the final answer is equal to the difference of the digital roots of 2 numbers.

Case II

1. Subtract two numbers 663 - 567.

2. Digital root of 663 is 6

3. Digital root of 567 is 9

4. Now subtract 6-9 is -3.

5. Here we observe that we get a negative digital root.

5. Subtract 663 - 567 = 96

6. Digital root of 96 is 6.

7. Here we observe that there is a mismatch in the digital roots ie. -3 & 6.

8. Always remember in subtraction we may get negative digital root so to make it positive we will take the complement of digital root with 9 ie. 9-3 =6. Now both the digital roots are same and we get the answer right.