I don't like Mathcounts, so I guess-and-check.
Ok, not guess and check but educated guessing??
Let's make estimates.
55 and 65? 3575.
60 x 70? 4200.
In between.
60 x 65? 3900. We need more.
61 x 65? 3965. MORE.
62 x 65? 4030. Close!!
63 x 65? Got it!
I guess and check, but the most efficient way would be to MAKE A TABLE. Multiples of 4095 with numbers in between 50 and 70!! Hope this helped!