Question

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

Answer 1

Multiply separately:
`3.8xx5.5=20.9`
and `10^4xx10^-1=` remembering that `a^mxxa^n=a^(m+n)`
So you get: `10^4xx10^-1=10^(4-1)=10^3`
Finally you get:
`20.9xx10^3=2.09xx10^4` moving the point to the left and adding 1 to the exponent of `10`.