Answer:
3.6 × 10^9
Step-by-step explanation:
When multipliying two numbers in scientific notation, the exponents in the factor of 10 will be added when the two expressions are multiplied.
Thus (1.2 ⋅ 10^28) ⋅ (3 ⋅ 10^−19) = ( 1.2 × 3 )
( 10^28 × 10^-19 ) = 3.6 × 10^(28-19) = 3.6 × 10^9
