Question 11
(a) When 14, 53 and 79 are divided by the same positive integer $N$, they leave the same remainder. Find the greatest possible $N$.
(b) The four-digit number $\overline{abab}$ has exactly six positive divisors. Find its smallest possible value.
(b) The four-digit number $\overline{abab}$ has exactly six positive divisors. Find its smallest possible value.