111 explained.

111 in everyday use

One hundred eleven is the non-emergency medical helpline number in England, Scotland, and Wales, and it is the emergency number in New Zealand. In cricket a score of 111 is a "Nelson", traditionally regarded as unlucky, and the umpire David Shepherd famously hopped on one leg whenever the total reached it. In binary the digits 111 mean seven, and as a repdigit — all the same digit — it is the sort of number people notice on clocks and odometers.

It is the smallest three-digit repunit, a number made of ones, and it factors as 3 × 37. That factor pair explains a party trick: 37 times any multiple of three from 3 to 27 gives a repdigit, since 37 × 3 = 111, 37 × 6 = 222, and so on up to 37 × 27 = 999. It is also the magic constant of the 6 × 6 magic square: each row, column, and diagonal of a square using 1 to 36 sums to 111, and the whole square to 666.