Greatest Common Divisor (GCD) of 123 and 78
The greatest common divisor (GCD) of 123 and 78 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 78?
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 ÷ 78 = 1 remainder 45 |
| 2 | 78 ÷ 45 = 1 remainder 33 |
| 3 | 45 ÷ 33 = 1 remainder 12 |
| 4 | 33 ÷ 12 = 2 remainder 9 |
| 5 | 12 ÷ 9 = 1 remainder 3 |
| 6 | 9 ÷ 3 = 3 remainder 0 |
Examples of GCD Calculations
| Numbers | GCD |
|---|---|
| 145 and 116 | 29 |
| 150 and 81 | 3 |
| 75 and 111 | 3 |
| 94 and 73 | 1 |
| 126 and 83 | 1 |