(4 x 10^7 (2.1 x 10^6) in scientific notation
(4 x 10^7) * (2.1 x 10^6) can be calculated as follows:
Multiply the numbers: 4 x 2.1 = 8.4
Add the exponents: 10^7 * 10^6 = 10^(7+6) = 10^13
Putting it all together, the result is 8.4 x 10^13 in scientific notation.