Its normal is symmetrical about the straight line x = 75,

Also, the number of people with scores between 60 and 90 accounts for about 35 of the total number.

According to symmetry:

The number of people with grades above 90 is about12 (1-35) =15 of the total number.

The students who scored not less than 90 points in this math exam are about:

15× 10000=2000.

So the answer is: 2000.