SUMMARY
The divisibility test for 11 states that a number is divisible by 11 if the alternating sum of its digits is divisible by 11. For example, to check if 209 is divisible by 11, one must subtract and add the digits alternately: 2 - 0 + 9 = 11. Since 11 is divisible by 11, the original number 209 is also divisible by 11. This method is applicable to any integer.
PREREQUISITES
- Understanding of basic arithmetic operations (addition and subtraction)
- Familiarity with the concept of divisibility
- Knowledge of how to manipulate digits of a number
- Basic number theory principles
NEXT STEPS
- Research additional divisibility rules for other prime numbers
- Explore advanced number theory concepts such as modular arithmetic
- Learn about the applications of divisibility tests in cryptography
- Study algorithms for efficient number factorization
USEFUL FOR
Mathematicians, educators, students learning number theory, and anyone interested in arithmetic properties of numbers.