1️⃣ Divisibility – Core Concept
A number A is divisible by B if division of A by B leaves remainder 0.
🔹 CAT Insight:
Divisibility is often tested indirectly through conditions, options elimination, or constraints, not direct rule-based questions.
2️⃣ Important Divisibility Rules (CAT-Relevant)
Divisible by 2
Last digit is even (0, 2, 4, 6, 8)
Divisible by 3
Sum of digits divisible by 3
Divisible by 4
Last two digits divisible by 4
Divisible by 5
Last digit is 0 or 5
Divisible by 6
Divisible by both 2 and 3
Divisible by 9
Sum of digits divisible by 9
Divisible by 11
Difference of sum of digits in alternate positions is 0 or a multiple of 11