THE MAGICAL LORE OF 6174
In a small fishing town of Dahanu, Maharashtra, a secondary school teacher named Dattatreya Ramchandra Kaprekar (DR Kaprekar) loved mathematics so much that he would spend hours exploring number theories and puzzles.
Born in 1905 to a clerk and homemaker, Kaprekar was a precocious child who dabbled in his own theories about mathematics. When Kaprekar was high years old, his mother passed away and he was brought up by his astrology-obsessed father.
In 1927, as an undergraduate, he won the Wrangler R.P. Paranjpye Mathematical Prize for an original piece of work in mathematics. Two years later, Kaprekar graduated with a BSc from the University of Mumbai and worked his whole life as a secondary school teacher.
Soon after World War II, Kaprekar stumbled upon the magic of number 6174. This captivating number had the hidden charm of a riddle, which went like this: Rearrange a 4-digit number (must be at least two unique digits) in ascending and descending order, then subtract the smaller number from the bigger one. Keep repeating the process and the final answer will always be 6174.
Let’s try with 1977.
9771 – 1779 = 7992
9972 – 2799 = 7173
7731 – 1377 = 6354
6543 – 3456 = 3087
8730 – 0378 = 8352
8532 – 2358 = 6174 (yes!)
Let’s do another: 7346
7643–3467 = 4176
7641–1467 = 6174 (ooh, that was fast!)
It is said that applying Kaprekar’s process to almost any four-digit number will result in 6174 after at most 7 steps. Give it a go!
Rumour has it that when Kaprekar introduced the magic number at a 1949 conference in Madras, many mathematicians criticised that the 6174 discovery was useless and trivial. In a way, the Kaprekar’s Constant seemed more of a parlour trick with no real practical applications.
Nonetheless, Kaprekar soldiered on and wrote over 100 papers (many private) on mathematics, including the books “Recreational Mathematics” and “The Kaprekar Constant”.
He was well-loved in the city of Devlali, where he taught, and would often be seen cycling with a bag full of mathematical papers, puns, and wordplay.
The mathematical world only knew about Kaprekar after Martin Gardner, a famous science writer, wrote an article about him in Scientific American in March 1975 issue.
Kaprekar died in 1986 at the age of 81, and will always be remembered as a pioneer in the field of recreational mathematics.
