Thomas Andrews
Reputation
98/100 score
7 118 229
Impact
~1.3m people reached

 112 Why do both sine and cosine exist? 77 Why is there no “remainder” in multiplication 61 $-1$ as the only negative prime. 60 Find an integer such that when squared, the first 4 digits are '6666'. 59 Best Fake Proofs? (A M.SE April Fools Day collection)

### Reputation (97,787)

 +10 What is the probability that the max of $n$ numbers from some distribution is a greater than another number from the same distribution? +10 Show that the set of all finite subsets of $\mathbb{N}$ is countable. +10 Prove that any integer greater than or equal to $7$ can be written as a sum of two relatively prime integers, both greater than $1$. +10 Show that $(a+b+c)^3 = a^3 + b^3 + c^3+ (a+b+c)(ab+ac+bc)$

### Questions (24)

 41 Functions $f:\mathbb{N}\rightarrow \mathbb{Z}$ such that $\left(m-n\right) \mid \left(f(m)-f(n)\right)$ 28 Prove $\frac{a^3+b^3+c^3}{3}\frac{a^7+b^7+c^7}{7} = \left(\frac{a^5+b^5+c^5}{5}\right)^2$ if $a+b+c=0$ 18 Is the numerator of $\sum_{k=0}^n \frac{(-1)^k}{2k+1}\binom{n}{k}$ a power of $2$? 16 Bézout's identity proof that if $(a,b,c)=1$ then $ax+bxy+cz=1$ has integer solutions 14 Simple(r) proof that $\pi(2^n)\geq n$?

### Tags (437)

 825 calculus × 229 592 abstract-algebra × 192 791 real-analysis × 230 457 limits × 128 782 elementary-number-theory × 223 412 combinatorics × 125 745 number-theory × 177 382 algebra-precalculus × 116 624 sequences-and-series × 168 331 trigonometry × 58

### Accounts (18)

 Mathematics 97,787 rep 7118229 Stack Overflow 710 rep 421 English Language & Usage 181 rep 3 MathOverflow 169 rep 4 Computer Science 136 rep 4