23 How many permutations are there for the letters in the word “meеt”? 21 A quick way, say in a minute, to deduce whether $1037$ is a prime number 8 Is the percentage symbol a constant? 8 Is “$f$” the function or is “$f(x)$” the function? 5 What do the small numbers/letters in a math or science formula mean???

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### Questions (65)

 16 Which positive integers can NOT be written as a sum of consecutive positive integers 11 Is the hyperbola isomorphic to the circle? 5 Cutting a multiple twisted Möbius strip in half 5 Prove that a presheaf is a sheaf 4 The sum of the cubes of three consecutive integers is divisible by $9$

### Tags (148)

 64 combinatorics × 42 21 primality-test 38 permutations × 23 20 discrete-mathematics × 22 38 algebra-precalculus × 16 14 calculus × 10 35 elementary-number-theory × 22 14 functions × 4 28 notation × 7 13 combinations × 16

### Bookmarks (12)

 109 A multiplication algorithm found in a book by Paul Erdős: how does it work? 80 Do most numbers have exactly $3$ prime factors? 50 Examples of group-theoretic results more easily obtained through topology or geometry 28 Iterated Euler's totient function 24 Prove that $2018^{2019}> 2019^{2018}$ without induction, without Newton's binomial formula and without Calculus.