This is pretty easy.
An exponent in this case shows how many zeros there should be, or how many places the decimal place be moved to the right (left if exponent's negative).
1. 42,000,000
2. 80
3. 3 x [tex]10^{4}[/tex]
4. 7 x [tex]10^{7}[/tex]
Hope this helps and please consider marking branliest.
