Ok, girls. (And guys, and frogs) Time to solve this problem - with LOGIC.
Let's do a binary search algorithm. Someone start with the number halfway between 1523 and 1200; I'll start the numbers between 1542 and 1536. (Less likely to be here as there are fewer entries)
Whomever Devlyn says is closest, we then take the midpoints on either side of her and repeat.
1539?