2026/018) Let $lcm(a,b)$ denote the least common multiple of a and b. Find the sum of all positive integers x such that $x \le 100$ and $lcm(16,x)=16x.$

 x must be co-prime to 16 . That means x is odd and every odd number satisfies the criteria . So result  is sum of all odd numbers less than 100. That is 2500