Question

What is the product written in scientific notation? (5.91×10−3)⋅(8.7×1010)

Answer 1

$(5.91\cdot10^{-3})\cdot(8.7\cdot10^{10})=(5.91\cdot8.7)\cdot(10^{-3}\cdot10^{10})\\\\=51.417\cdot10^{-3+10}=51.417\cdot10^7=5.1417\cdot10\cdot10^7\\\\=\boxed{5.1417\cdot10^8}\to\boxed{B.}$

$Used:\\\text{Associative property}\ (a\cdot b)\cdot c=a\cdot(b\cdot d)\\\\a^n\cdot a^m=a^{n+m}$

Answer 2

(5.91×10^−3)⋅(8.7×10^10)

= (5.91 x 8.7) x 10^(- 3 + 10)

= 51.417 x 10^7

= 5.1417 x 10^8

Answer is

B. 5.1417 × 10^8