Question 11
How many pairs of positive integers $(a, b)$ are there, both not exceeding $10$, such that $a \leq \operatorname{gcd}(a, b) \leq b$ and $a \leq \operatorname{lcm}(a, b) \leq b$?
Math Olympiad Vault · MathNet 2018-part-04 — 181 problems (EN–VI)