The least common multiple (LCM) is the smallest positive integer that is divisible by both a and b, where a and b are two integers. It is also known as the lowest common multiple or the smallest common multiple. The LCM is used in many situations, such as finding the lowest common denominator of two or more fractions, adding, subtracting, and comparing two or more fractions, and finding the minimum distance each person should walk so that all can cover the same distance in complete steps. There are different methods to find the LCM of two or more numbers, including listing the multiples, prime factorization, and division method. The prime factorization method involves breaking down numbers into their prime factors and constructing the smallest number with all the factors. Listing multiples involves finding the smallest shared multiple. Both methods help find the LCM of numbers like 18 and 12. The LCM of two coprime numbers is always their product.