The square root is when we multiply the lowest digit twice or two times to arrive at the number. Cube root is when we multiply the lowest number thrice or three times to arrive at the number. Numbers obtained when a number is multiplied by itself three times are known as cube numbers. Numbers like 1729, 4104, 13832, are known as Hardy – Ramanujan Numbers. They can be expressed as the sum of two cubes in two different ways.