Been a while since I’ve needed to not use a calculator. Why is -2X10^-18 (3/16) = 4.09X10^-19?

Answer:see the explanationStep-by-step explanation:we have[tex]2.18*10^{-18}(\frac{3}{16})[/tex]we have that[tex]\frac{3}{16}=0.1875[/tex]Convert to scientific notation[tex]0.1875=1.875*10^{-1}[/tex]substitute[tex]2.18*10^{-18}(1.875*10^{-1}})[/tex]Remember thatTo multiply two numbers in scientific notation, multiply their coefficients and add their exponents[tex]2.18*10^{-18}1.875*10^{-1}}=(2.18*1.875)*10^{(-18-1)}=4.0875*10^{-19}[/tex]Round the number 4.0875 two decimal placesso[tex]4.0875*10^{-19}=4.09*10^{-19}[/tex]