How many ordered quadruples $(a,b,c,d)$ of nonnegative integers are there such that $abcd = 288$?
41939
How many ordered quadruples $(w, x, y, z)$ of non-negative integers are there such that $wxyz = 288$? Why?
106896
Number of solutions of $x_1+2x_2+\cdots+kx_k=n$?
96326
Number of $q$-th residues modulo $n$
23427
How to prove there are no more positive integers that are products of 2 and 3 consecutive numbers?
18530
Given 4 integers, $a, b, c, d > 0$, does $\frac{a}{b} < \frac{c}{d}$ imply $\frac{a}{b} < \frac{a+c}{b+d} < \frac{c}{d}$?
153241
Four different positive integers a, b, c, and d are such that $a^2 + b^2 = c^2 + d^2$
69721
$(a,b) \mathbin\# (c,d)=(a+c,b+d)$ and $(a,b) \mathbin\&(c,d)=(ac-bd(r^2+s^2), ad+bc+2rbd)$. Multiplicative inverse?
14783
A Number Theory problem (GCD)
62036
Finding the number of non-negative integral solutions of $x + y + z = 10$
9218
How many ways to arrange ABCD such that A precedes B, and C precedes D
95409
Find no. of non negative integer solutions of $a+2b+3c = 200$
61268
Is there a combinatorial interpretation of the triangular numbers?
150528
Pythagorean triples $(a,b,c)$ and divisibility of $a$ or $b$ by $3$.
118716
If $ABCD$ is a cyclic quadrilateral, then $AC\cdot(AB\cdot BC+CD\cdot DA)=BD\cdot (DA\cdot AB+BC\cdot CD)$
103581
Which positive integers can NOT be written as a sum of consecutive positive integers
92166
Number of odd binomial coefficients is a power of $2$
149489
30 positive integers