How do you simplify and write $\frac{1.0 \times 10^{- 15}}{4.2 \times 10^{- 7}}$ $(1.0times10^-15)/(4.2times10^-7)$ in scientific notation?

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Answer 1 · 2016-07-27T18:00:00

$2.38 \cdot 10^{- 9}$ $2.38*10^-9$

How I usually answer questions like this I ignore the exponents first and divide the numbers as usual
$\frac{1.0}{4.2} = 0.238$ $1.0/4.2=0.238$

Now I take care of the exponents since we're dividing you subtract the exponents
$- 15 - (- 7) = - 8$ $-15-(-7)=-8$

So now we have
$0.238 \cdot 10^{- 8}$ $0.238*10^-8$

We have to move the decimal back to make it proper scientific notation, so the answer is
$2.38 \cdot 10^{- 9}$ $2.38*10^-9$

How do you simplify and write 1.0×10−154.2×10−7(1.0times10^-15)/(4.2times10^-7) in scientific notation?