Question

What is 58,000,000,000 estimated as the product of a single digit and a power of 10?

Answer 1

$The\ scientific\ notation:a\cdot10^n\ where\ 1\leq a \ \textless \ 10\ and\ n\in\mathbb{Z}.\\\\5\underbrace{8,000,000,000}_{\leftarrow10}=5.8\cdot10^{10}\approx6\cdot10^{10}\to\fbox{D.}$

Answer 2

The number 58,000,000 is number that may be expressed in its scientific notation as  5.8 x 10^9. However, we are asked to answer such that the product be of single digit only. That is obtained by rounding the number 5.8 to 6. Thus, the answer is 6 x 10^9.