The first one is
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This this because you simply add the exponents and keep the base.
The answer to the second one is

This is because you multiply the coefficients 6x7 = 42 then add the exponents -8 + 3 = -5 and get

However a negative exponent must be moved to the denominator leaving you with the answer I stated.
The answer to the next question is

The first step would be to multiple your coefficients 7 x 8 and exponents. By multiplying the 10 powers you just add the exponents. This would result in

However, this is not in scientific method because 56 > 9. To fix this you, move the decimal place over one on 56 to get 5.6 and add an exponent to 11 because you made 56 smaller by a factor of 10.
The answer to the final question is

Follow the same procedure I stated above! 9 × 7 = 63. You still add one though so -14 + 1 = -13.