# 1729 — The First Taxicab Number

Episode five of A Further Five Numbers, the BBC radio series presented by Simon Singh.

Curious properties sometimes lurk within seemingly undistinguished numbers. 1729 sparked one of maths most famous anecdotes: a young Indian, Srinivasa Ramanujan, lay dying of TB in a London hospital. G.H. Hardy, the leading mathematician in England, visited him there. "I came over in cab number 1729," Hardy told Ramanujan. "That seems a rather dull number to me."

"Oh, no!" Ramanujan exclaimed. "1729 is the smallest number you can write as the sum of two cubes, in two different ways." Most of us would use a computer to figure out that 1³ + 12³ = 9³ + 10³ = 1729. Ramanujan did it from his sickbed without blinking.

## Possibly related…

1. ### 1729 — The First Taxicab Number

Episode five of A Further Five Numbers, the BBC radio series presented by Simon Singh.

Curious properties sometimes lurk within seemingly undistinguished numbers. 1729 sparked one of maths most famous anecdotes: a young Indian, Srinivasa Ramanujan, lay dying of TB in a London hospital. G.H. Hardy, the leading mathematician in England, visited him there. "I came over in cab number 1729," Hardy told Ramanujan. "That seems a rather dull number to me."

"Oh, no!" Ramanujan exclaimed. "1729 is the smallest number you can write as the sum of two cubes, in two different ways." Most of us would use a computer to figure out that 1³ 12³ = 9³ 10³ = 1729. Ramanujan did it from his sickbed without blinking.

2. ### 1 — The Most Popular Number

Episode one of A Further Five Numbers, the BBC radio series presented by Simon Singh.

Literally, the most popular number, as it appears more often than any other number. More specifically, the first digit of all numbers is a 1 about 30% of the time, whereas it is 9 just 4% of time. This was accidentally discovered by the engineer Frank Benford. It works for all numbers – mountain heights, river lengths, populations, etc.

3. ### 1 — The Most Popular Number

Episode one of A Further Five Numbers, the BBC radio series presented by Simon Singh.

Literally, the most popular number, as it appears more often than any other number. More specifically, the first digit of all numbers is a 1 about 30% of the time, whereas it is 9 just 4% of time. This was accidentally discovered by the engineer Frank Benford. It works for all numbers – mountain heights, river lengths, populations, etc.