Question

The radius of Earth is expressed as 0.64 × 10⁷ m in scientific notation. What is its order of magnitude and number of significant figures?

Options

• Order of magnitude = 6; significant figures = 3

• Order of magnitude = 7; significant figures = 2

• Order of magnitude = 7; significant figures = 3

• Order of magnitude = 6; significant figures = 2

Answer 1

Order of magnitude = 7; significant figures = 2

Explanation: 

When a quantity is expressed as A × 10ⁿ (where 0.5 ≤ A < 5), the exponent n is the order of magnitude. Here, n = 7. The number 0.64 contains only 2 significant digits (6 and 4), so the measurement has 2 significant figures.