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