Greatest Common Divisor (GCD) of 123 and 129
The greatest common divisor (GCD) of 123 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 123 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 | 123 ÷ 129 = 0 remainder 123 |
| 2 | 129 ÷ 123 = 1 remainder 6 |
| 3 | 123 ÷ 6 = 20 remainder 3 |
| 4 | 6 ÷ 3 = 2 remainder 0 |
Examples of GCD Calculations
| Numbers | GCD |
|---|---|
| 188 and 110 | 2 |
| 145 and 185 | 5 |
| 161 and 114 | 1 |
| 170 and 127 | 1 |
| 11 and 30 | 1 |