I look at 900k$ and think wow from the perspective of my very well paid job in France.
Getting 900k$ a year would bring great things to me and probably make me retire earlier. This will not be life-changing though.
And then I think about people who earn 5% of what I do and for them multiplying their income by two would probably be truly life changing for them.
And then these 900k$ do not look that wow anymore.
And the dollar sign goes on the side I put it: nine hundred thousand dollars. The fact that you want to write $900k is just an idea specific to the finance world (such as using parentheses for negative numbers).
Do you usually write m4, in7 or lb9?