0.000042/0.0084=2 Scientific notation. DIvide. My answer is 2 is this

scientific notation is when you set the number times a power of 10.

Example:
100 = 1*10^2
.0003 = 3*10^-4

so your answer should be
0.000042/0.0084=.005
Which in scientific notation is 5*10^-3

I would recommend looking at scientific notation online.

55*10^4

8.4 times 10 - 6