On a graph with y-values ranging from 1,013,020 to 9,618,115, what is a reasonable scale to use on a y-axis with 10 tick marks?

Divide the range range between 10 fo find the appropriate scale.

[9618115 - 1013020]/10 = 8605095/10 = 860509.5

Then use scale 1: 1000000. So your marks will be

1 = 1000000

2 = 2000000

3 = 3000000

... 10 = 10000000