exponents

o get rid of negative exponents you have to make the equation in to a fraction. 
10^-3 becomes 1 over (or divided by) 10^3. 
10^3 is 1000, and 1 divided by 1000 = 0.001

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${10}^{-3} = \frac{1}{{10}^{3}} = \frac{1}{1000} = 0.001$

10^-3 = 0.001

Hope this helps.