He was born in Copenhagen, Denmark. He studied at the Institute for Theoretical Physics of the University of Copenhagen (later to become the Niels Bohr Institute), and Technical University of Denmark. Yale awarded him an honorary doctorate in 1972. He died in his home on Funen, Denmark in 1996.

He was a direct descendant of Piet Pieterszoon Hein, the Dutch naval hero of the 17th century.

Piet Hein, who, in his own words, "played mental ping-pong" with Niels Bohr in the inter-War period, found himself confronted with a dilemma when the Germans occupied Denmark. He felt that he had three choices: Do nothing, flee to "neutral" Sweden or join the Danish resistance movement. As he explained in 1968, "Sweden was out because I am not Swedish, but Danish. I could not remain at home because, if I had, every knock at the door would have sent shivers up my spine. So, I joined the Resistance."

Taking as his first weapon the instrument with which he was most familiar, the pen, he wrote and had published his first "grook" [gruk in Danish]. It passed the censors who did not grasp its real meaning.

CONSOLATION GROOKLosing one gloveis certainly painful,but nothingcompared to the pain,of losing one,throwing away the other,and findingthe first one again.

The Danes, however, understood its importance and soon it was found as graffiti all around the country. The deeper meaning of the grook was that even if you lose your freedom ("losing one glove"), do not lose your patriotism and self-respect by collaborating with the Nazis ("throwing away the other"), because that sense of having betrayed your country will be more painful when freedom has been found again someday. Denmark got the message.

After Liberation, Scandinavian architects, tired of square buildings but cognizant that circular buildings were impractical, asked Piet Hein for a solution. Applying his mathematical prowess to the problem, Piet Hein created the superellipse which became the hallmark of modern Scandinavian architecture.

In addition to the thousands of grooks he wrote, Piet Hein devised the games of Hex, Tangloids, Morra, Tower, Polytaire, TacTix, Nimbi, Qrazy Qube, Pyramystery, and the Soma cube. He advocated the use of the superellipse curve in city planning, furniture making and other realms. He also invented a perpetual calendar called the Astro Calendar and marketed houseware based on the superellipse and Superegg.

Piet Hein was married four times, and had five sons from his last three marriages.

1937: married Gunver Holck, divorced.

1942: married: Gerda Ruth (Nena) Conheim, divorced.Sons: Juan Alvaro Hein, born 9 January 1943; Andrés Humberto Hein, born 30 December 1943.

1947: married Anne Cathrina (Trine) Krøyer Pedersen, divorced.Son: Lars Hein, born 20 May 1950.

1955: married Gerd Ericsson, who died 3 November 1968.Son: Jotun Hein, born 19 July 1956; Hugo Piet Hein, born 16 November 1963.

Jotun Hein proved the Soma cube's "Basalt Rock" construction impossible at age 12, and this was published in the puzzle's instruction manual as "Jotun's Proof." Today he is Professor of Bioinformatics at the Department of Statistics of the University of Oxford and a professorial fellow of University College, Oxford. He was previously Director of Bioinformatics Research Centre at Aarhus University, Denmark.