Variant 11.7.2. 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 $N / a_{4}$ can take?

(b) (2 points) List all possible values of $a_{4}$ in the interval $[1 ; 1300]$, for which the value of $N / a_{1}$ can take its smallest value.
Answer: (a) 7. (b) $360, 720, 1080$.