MathCastle
Number TheorySuperchallengeFactors & Multiples

Factors & Multiples · Superchallenge problem

How many ordered pairs (a,b)(a, b) of integers with 1≤a≤1001 \le a \le 100 and 1≤b≤1001 \le b \le 100 satisfy lcm⁡(a,b)=30gcd⁡(a,b)\operatorname{lcm}(a, b) = 30 \gcd(a, b)?