From India
D. R. Kaprekar
A schoolteacher who loved number curiosities. Take a four-digit number (not all digits the same), sort its digits largest-first and smallest-first, subtract, and repeat.
You always reach 6174 within seven steps, and then you stay there.
Kaprekar’s constant
No portrait of D. R. Kaprekar survives, so we show the mathematics instead.
Where you’ll meet D. R. Kaprekar here
Number theoryLogic
They turn up beside problems and lessons on these topics.
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Harish-Chandra
He trained as a physicist under Paul Dirac before switching to mathematics.
His work on the symmetries of Lie groups now shapes much of number theory and physics. The Harish-Chandra Research Institute in Prayagraj bears his name.
Unknown author, CC BY 4.0, via Wikimedia Commons (resized)