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QUANTITATIVE REASONING · GMAT-Q-INT-01

Integers, Factors and Multiples

GMAT lesson development preview · DRAFT · Original learning and assessment material

Concepts and problem-solving strategy

Divisibility and multiples

Consecutive integer sums

Counting multiples in a range

Think Like a GMAT Test-Taker

Translate number-property wording into integers, factors, or multiples before calculating.

Faster Methods

Count multiples by floor division rather than listing values.

Use factor pairs to test integer feasibility.

Keep inclusive range endpoints explicit.

Worked example 1

How many multiples of 7 occur from 20 through 100?

Count 21 to 98 inclusive.

Worked example 2

Find the sum of the first 20 positive integers.

Use the arithmetic series total.

Common Traps

  • 1 is neither prime nor composite.
  • A factor and a multiple describe inverse relationships.
  • An even integer need not be positive.
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