Answer
$1.30032 \times 10^{-20}$
Work Step by Step
$(7.2 \times 10^{-9})(1.806 \times 10^{-12})$
Simplify by adding together the two decimals 7.2 and 1.806. Then combine the exponents using addition.
$(7.2 \times 1.806 \times 10^{-21})$
$(13.0032 \times 10^{-21})$
Move the decimal place to the left once, which means you need to add to the exponent, making it:
$(1.30032 \times 10^{-21+1})$
$(1.30032 \times 10^{-20})$
