# How do you multiply (3.8*10^4)(5.5*10^-1)?

$3.8 \times 5.5 = 20.9$
and ${10}^{4} \times {10}^{-} 1 =$ remembering that ${a}^{m} \times {a}^{n} = {a}^{m + n}$
So you get: ${10}^{4} \times {10}^{-} 1 = {10}^{4 - 1} = {10}^{3}$
$20.9 \times {10}^{3} = 2.09 \times {10}^{4}$ moving the point to the left and adding 1 to the exponent of $10$.