Hello!
I believe that you can rewrite 4,005,000 in scientific notation as 4.005*10^6.
You'll need to move the decimal place of 4,005,000 to the left until there is one non-zero digit on the left of the decimal. The number of times you move the decimal will determine the exponent on the 10. Once you've done that, you'll end up with the scientific notation...
4.005*10^6
I hope this help!
