Greatest Common Divisor (GCD) of 81 and 129
The greatest common divisor (GCD) of 81 and 129 is 3.
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 81 and 129?
We use the Euclidean algorithm, which involves the following steps:
- Divide the larger number by the smaller number.
- Replace the larger number with the smaller number and the smaller number with the remainder from the division.
- Repeat this process until the remainder is zero.
- The non-zero remainder just before zero is the GCD.
Step-by-Step Euclidean Algorithm
| Step | Calculation |
|---|---|
| 1 | 81 ÷ 129 = 0 remainder 81 |
| 2 | 129 ÷ 81 = 1 remainder 48 |
| 3 | 81 ÷ 48 = 1 remainder 33 |
| 4 | 48 ÷ 33 = 1 remainder 15 |
| 5 | 33 ÷ 15 = 2 remainder 3 |
| 6 | 15 ÷ 3 = 5 remainder 0 |
Examples of GCD Calculations
| Numbers | GCD |
|---|---|
| 159 and 162 | 3 |
| 78 and 188 | 2 |
| 19 and 77 | 1 |
| 136 and 10 | 2 |
| 163 and 153 | 1 |