KNOWN WAY

To divide a large number by 9 easily, you can use the fact that a number is divisible by 9 if the sum of its digits is divisible by 9. Here’s how:

1. Add all the digits of the number together.
2. If the sum is a multiple of 9, then the original number is divisible by 9.
3. The remainder when dividing by 9 is the remainder when dividing the sum of the digits by 9.

For example, with the number 3.752.247.929:

• Add the digits: 3 + 7 + 5 + 2 + 2 + 4 + 7 + 9 + 2 + 9 = 50
• Now, 50 divided by 9 gives 5 remainder 5.
• So, 3752247929 divided by 9 leaves a remainder of 5.

LESS KNOWN WAY

You can easily determine the remainder when dividing by 9 by using this rule: exclude all the 9s you find!

Step 1: Write down the number: 3 7 5 2 2 4 7 9 2 9

Step 2: Sum two or three digits (or how much it takes) to find 9s:

• 7 + 2 = 9 (exclude these digits)
• 4 + 3 + 2 = 9 (exclude these digits)
• 9 = 9 (exclude these digits)

Step 3: Remaining digits after exclusion:

• 5

which is the answer of this question !