2.5 x 10^3 = 2500
3.5 x 10^-7 = .000 000 35
2500 X .000 000 35 = 2500*.00000035 = 0.000875
...or just enter it into the Web2.0 calc as you entered it in your Q
2.5*10^3*3.5*10^-7 = 0.000875
\(2.5\times 10^3=2500\) and \(3.5\times 10^{-7}=0.00000035\) so multiplying them you get \(0.000875\)
You are very welcome!
:P