Answer:
7.38×10^3
Explanation:
The usual rules of exponents apply.
(20.5×10^7)(3.6×10^-5) = (2.05)(3.6)(10^(8-5)) = 7.38×10^3
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Additional comment
You can have your scientific or graphing calculator or your spreadsheet compute this product for you and display the result in scientific notation. You can enter the numbers in scientific notation or in standard form in any calculator or spreadsheet. (For a spreadsheet, the first number would be entered 20.5e7 or 2.05e8.)
The applicable rule of exponents is ...
(10^a)(10^b) = 10^(a+b)
Just as the place values increase by factors of 10 going to the left of the decimal point, so they decrease by factors of 10 to the right. The number 3 in 0.000036 is in the 5th place to the right of the decimal point, so has a place value of 10^-5.