/**
 * The product of all the whole numbers between 1 and n, where n must always be positive.
 * A factorial is represented by the sign (!)
 *
 * @param  {number} value Input value
 *
 * @return {number}       Factorial result
 */
declare function factorial(value: number): number;
/**
 * Permutations of n items taking r items at a time
 * Is represented by the sign (nPr)
 *
 * @param  {number} n Total items
 * @param  {number} r Number of items to be taken of
 *
 * @return {number}   Number of ways to select
 */
declare function permutations(n: number, r: number): number;
/**
 * Combinations of n items taking r items at a time
 * Is represented by the sign (nCr)
 *
 * @param  {number} n Total items
 * @param  {number} r Number of items to be taken of
 *
 * @return {number}   Number of ways to select
 */
declare function combinations(n: number, r: number): number;
export { factorial, permutations, combinations };