/**
 * Calculates the greatest common divisor (GCD) of two numbers using the Euclidean algorithm.
 * @param {number} a - The first number.
 * @param {number} b - The second number.
 * @returns The greatest common divisor of a and b.
 * @example
 * const result = gcd(48, 18); // 6
 */
export declare function gcd(a: number, b: number): number;