6721 is divisible by

Step-by-Step Solution

To determine which number divides 6721, we apply standard divisibility rules for each option.

1. Check Divisibility by 8:

   • Rule: The last three digits must be divisible by 8.

   • Last three digits of 6721 = 721.

   • 721 / 8 = 90 with a remainder of 1. Not divisible by 8.

2. Check Divisibility by 9:

   • Rule: The sum of the digits must be divisible by 9.

   • Sum of digits = 6 + 7 + 2 + 1 = 16.

   • 16 is not divisible by 9.

3. Check Divisibility by 10:

   • Rule: The number must end in 0.

   • 6721 ends in 1, so it is not divisible by 10.

4. Check Divisibility by 11:

   • Rule: The difference between the sum of digits in odd positions and the sum of digits in even positions must be 0 or a multiple of 11.

   • Sum of digits in odd positions (from right): 1 + 7 = 8.

   • Sum of digits in even positions (from right): 2 + 6 = 8.

   • Difference = 8 - 8 = 0.

   • Since the difference is 0, the number 6721 is divisible by 11.