GMAT Number Properties: A Guide to Integer Logic

Number Properties are a critical component of GMAT Quant, testing your logical reasoning as much as your calculation skills. This guided path will teach you the core concepts and advanced strategies needed to master this topic.

Section 1: Number Classification & Core Concepts

The Building Blocks: Number Classification

Start with the fundamental types of numbers. This is the basic vocabulary for all Number Properties questions.

Classification Hierarchy

  • Real Numbers[-]
    All types below
    • Rational[-]
      5, 2.7, -92.4, 22/7
      • Integers[-]
        ..., -2, -1, 0, 1, 2, ...
        • Natural
          1, 2, 3...
        • Whole
          0, 1, 2, 3...
      • Fractions
        1/2, -7/3, 2.75
    • Irrational
      √2, √3, π, e

Real Numbers

All rational and irrational numbers. They can be represented on a continuous number line.

Examples
All types below

Number Line Visualization

-3
-2
-1
0
1
2
3

Hover over points to see values.

Integer Properties: Prime, Even & Odd

Dive deeper into the most important number type—integers. Learn what makes them Prime, Even, Odd, and more with interactive examples.

Further Classifications of Integers

💡 Key Takeaways

  • 1 is neither Prime nor Composite.
  • 2 is the only Even Prime number.
  • There are 25 Prime numbers between 1 and 100.

Odd & Even Calculation Properties

Master the rules for adding, subtracting, and multiplying odd and even numbers—a key skill for logical deduction in Data Sufficiency.

Addition Rules

+
=
?

Section 2: Factors, Divisibility & GMAT Strategy

Divisibility: A Complete Guide

Master the essential rules of divisibility (for 3, 4, 6, 8, 9, 11) and test your skills with our interactive checker.

Rule for 3
If the sum of all digits is divisible by 3, so is the number.
Rule for 4
If the number formed by the last 2 digits is divisible by 4, so is the original number.
Rule for 5
Ends in 0 or 5.
Rule for 6
Must be divisible by BOTH 2 (even) and 3.
Rule for 8
If the number formed by the last 3 digits is divisible by 8.
Rule for 9
If the sum of all digits is divisible by 9.
Rule for 11
Difference between sum of digits in odd positions and sum of digits in even positions is 0 or multiple of 11.

Factors & HCF: Interactive Tools

Learn about prime factorization, how to find the total number of factors, and how to calculate the HCF of two numbers.

Prime Factorization

Every integer > 1 is a unique product of primes.
e.g., 12 = 2² × 3

Total Factors Formula

If N = aᵖ × b^q, Total Factors = (p+1)(q+1).

GMAT Strategy: Data Sufficiency (NEW)

Apply your knowledge to the GMAT's unique question type. Learn to evaluate sufficiency for questions about primes, factors, and remainders.

Step 1The Problem

If x is an integer, is x a prime number?

(1) x is an even number.
(2) x is a factor of 14.

Step 2Analyze Statement (1)

If x is even, it could be 2 (which is prime) or it could be 4, 6, 8, etc. (which are not prime). Since we get both a 'yes' and a 'no' answer, this is INSUFFICIENT.

Step 3Analyze Statement (2)

The positive factors of 14 are 1, 2, 7, 14. x could be 2 or 7 (prime), or it could be 1 or 14 (not prime). INSUFFICIENT.

Step 4Combine Statements

We need a number that is both even AND a factor of 14. The only even factors of 14 are 2 and 14.

If x=2, the answer is 'yes'. If x=14, the answer is 'no'. Since we still don't have a unique answer, it is INSUFFICIENT.

Final Answer: (E)

Section 3: Advanced Rules & Remainders

Advanced Divisibility Patterns

Explore special cases and number patterns (like ABAB or ABCABC) related to divisibility that can act as powerful shortcuts.

Property of n Consecutive Integers

In any set of 'n' consecutive integers, exactly one number is divisible by 'n'. Try changing n and start.

GMAT Strategy: Remainder Problems

Learn the formal algebraic method for solving complex remainder questions, a classic high-level GMAT problem type.

Step 1Problem

When N is divided by 7, remainder is 2. Find rem of 3N divided by 7.

Step 2Step 1

$$ N = 7q + 2 $$

Step 3Step 2

$$ 3N = 21q + 6 $$

Step 4Conclusion

21q is divisible by 7. Remainder comes from 6.
Ans: 6
Interactive Practice

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