A dozen numbers, hand-picked.
Twelve of the 151 puzzles in Owlet's bank. Each one is a small door onto a large story — an unsolved conjecture, a famous quote, a strange coincidence. Click any card to try it in Practice Mode. Then head back to today's daily for the challenge everyone plays together.
1729 — Ramanujan's Taxicab
"Every positive integer is a friend of Ramanujan's." — G.H. Hardy
6174 — Kaprekar's Constant
Sort digits desc − asc, iterate. Every 4-digit number (non-repdigit) reaches 6174 in ≤7 steps.
3435 — The Münchhausen Number
The only Münchhausen number ≠ 1: 3³ + 4⁴ + 3³ + 5⁵ = 3435.
65537 — Fermat Prime F₄
The largest Fermat prime we've ever found. F₅ through F₃₂ are all composite.
142857 — The Cyclic Number
Multiply by 1–6 and the digits rotate. 142857 × 7 = 999999.
12345 — Deceptively Composite
12345 = 3 · 5 · 823. World's most common password, but also has an interesting factorization.
998001 — The Pattern Generator
1/998001 = 0.000001002003004... every 3-digit number in order.
1234321 — A Palindromic Square
1111² = 1234321. A perfect palindrome that is also a perfect square.
196 — The Lychrel Suspect
Reverse-and-add makes palindromes for almost every seed. 196 has resisted for billions of iterations.
271828 — Six Digits of e
First six digits of Euler's number, base of the natural logarithm.
2027 — Next Prime Year
The next prime year after 2017.
3141 — First Four Digits of π
π to four digits: 3.141...