### Questions (115)

 102 A multiplication algorithm found in a book by Paul Erdős: how does it work? 28 Are there rings whose multiplicative identity is not the number 1 or number 1-based? 26 What is this pattern found in the first occurrence of each $k \in \{0,1,2,3,4,5,6,7,8,9\}$ in the values of $f(n)=\sqrt{n}-\lfloor \sqrt{n} \rfloor$? 22 Why is this family of dynamical systems able to produce spirals and clusters of points? 22 Euler's Totient function $\forall n\ge3$, if $(\frac{\varphi(n)}{2}+1)\ \mid\ n\$ then $\frac{\varphi(n)}{2}+1$ is prime

### Reputation (5,372)

 +10 Are my calculations of a new constant similar to Mill's constant based on $\lfloor A^{2^{n}}\rfloor$ and Bertrand's postulate correct? +5 What methods are known to visualize patterns in the set of real roots of quadratic equations? +5 A multiplication algorithm found in a book by Paul Erdős: how does it work? +5 Visualizing tuples $(a,b,x,y)$ of the extended Euclidean algorithm in a four-dimensional tesseract. Are there hidden symmetries?

 17 Visually stunning math concepts which are easy to explain 11 Sequence that is neither increasing, nor decreasing, yet converges to 1 11 What are some easy but beautiful patterns in Pascal's Triangle? 7 Why is this family of dynamical systems able to produce spirals and clusters of points? 7 Simple theorems that are instances of deep mathematics

### Tags (155)

 40 prime-numbers × 81 12 elementary-number-theory × 61 26 sequences-and-series × 27 12 recreational-mathematics × 8 20 big-list × 5 12 soft-question × 6 18 visualization × 25 12 algebra-precalculus × 5 17 number-theory × 25 11 binomial-coefficients

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