Variant 11.7.3. Let $N$ be the least common multiple of ten different natural numbers $a_{1}<a_{2}<a_{3}<\ldots<a_{10}$.

(a) (2 points) What is the smallest value that $N / a_{5}$ can take?

(b) (2 points) List all possible values of $a_{5}$ in the interval $[1 ; 1500]$, for which the value of $N / a_{1}$ can take its smallest value.
Answer: (a) 6. (b) 420, 840, 1260.