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Greatest Common Divisor (GCD) of 78 and 40

The greatest common divisor (GCD) of 78 and 40 is 2.

What is the Greatest Common Divisor (GCD)?

The GCD of two integers is the largest positive integer that divides both numbers without leaving a remainder. It is useful in simplifying fractions, finding common factors, and in number theory.

How to Calculate the GCD of 78 and 40?

We use the Euclidean algorithm, which involves the following steps:

  1. Divide the larger number by the smaller number.
  2. Replace the larger number with the smaller number and the smaller number with the remainder from the division.
  3. Repeat this process until the remainder is zero.
  4. The non-zero remainder just before zero is the GCD.

Step-by-Step Euclidean Algorithm

StepCalculation
1 78 ÷ 40 = 1 remainder 38
2 40 ÷ 38 = 1 remainder 2
3 38 ÷ 2 = 19 remainder 0

Examples of GCD Calculations

NumbersGCD
74 and 411
68 and 382
87 and 591
114 and 486
132 and 831

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