I took my OA, for the new grad position yesterday taking both maths and the programming contest. The 2 questions from programming were really easy, similar to the links given below.
https://leetcode.com/problems/find-pivot-index/
https://leetcode.com/problems/palindromic-substrings/
The total time taken for the test is around 180 minutes (120 + 60), and 120 minutes is a lot to solve the programming problems. I found the maths test to be harder than the programming contest. Some examples in the Maths test:
1.) probability of selecting a bridge deck(13 cards), with no Aces, no kings, no queens and no jacks
2.) Mutlivariable calculus to find the area of f(x,y) (ex : x^2 + y^2) bounded by some curves (ex : y = x^2 and y = x)
3.) Given a matrix M = [1,0]'s (n x n size) find the least number k where M^k = I (identity matrix)
4.) Some combinatorial and permutations questions

I suggest anyone who's taking the maths test to prepare on probability, combinatorial problems, linear algebra, and multivariable calculus. This is my second time taking the contest (maths + programming )for GS, i took one for the Internship as well I came to know that the problems given on the contest involve probability and combinatorial maths a little more than others. I could solve the programming contest in 20 minutes whereas I took around 2 hours to solve 10 math problems (may be I'm slow, however you might be faster), lucky enough to have a lot of time hand ;)

All the best for your OA, and have a good day.