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Greatest Common Divisor (GCD) of 191 and 128

The greatest common divisor (GCD) of 191 and 128 is 1.

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 191 and 128?

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
1 191 ÷ 128 = 1 remainder 63
2 128 ÷ 63 = 2 remainder 2
3 63 ÷ 2 = 31 remainder 1
4 2 ÷ 1 = 2 remainder 0

Examples of GCD Calculations

NumbersGCD
57 and 251
165 and 521
74 and 511
29 and 1021
181 and 1361

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