Question

(1.5×10 ​0 ​​ )×(2.0×10 ​−5 ​​ )

Answer 1

If the 0 and -5 are exponents, you need to calculate

1.5 x 0.00002 = 0.00003 = 3.0 x 10⁻⁵

The easiest way to multiply scientific notation numbers is to just multiply the 1.5 and 3.0 (sometimes called the mantissa) and add the exponents.

1.5 x 2.0 = 3.0
10⁰ x 10⁻⁵ = 10⁰⁻⁵ = 10⁻⁵

If, however, the resulting mantissa is not in the range 1.0..10 you should shift the decimal point one more. (e.g., 18.0x10² becomes 1.8x10³)