Question

Multiply (1.2 ⋅ 1028) ⋅ (3 ⋅ 10−19). Express the answer in scientific notation.

a) 3.6 ⋅ 109
b) 3.6 ⋅ 1010
c) 36 ⋅ 109
d) 36 ⋅ 1010

Answer 1

The answer would be A. 3.6 × 10^9

Answer 2

Answer: a) $3.6\cdot10^9$

Step-by-step explanation:

The given multiplication problem is

$(1.2\cdot10^{28})(3\cdot10^{-19})$

First we open the parenthesis, and then multiply corresponding terms.

$1.2\cdot10^{28}\cdot3\cdot10^{-19}\\=(1.2\cdot3)\cdot(10^{28}\cdot10^{-19})\\=3.6\cdot10^{28+(-19)}.....[\text{by using law of exponents }a^ma^n=a^{m+n}]\\=3.6\cdot10^{28-19}\\=3.6\cdot10^9$

Thus, a) is the right answer.