What does scientific notation describe?

• A. A method of writing very large or very small numbers using powers of 10.
• B. A method of rounding numbers to the nearest integer.
• C. A unit conversion technique.
• D. A way to describe fractions in decimal form only.

Answer: (A)

Scientific notation expresses very large or very small numbers by using powers of ten. It writes a number as a decimal between 1 and 10 (the mantissa) multiplied by 10 raised to an integer exponent. This makes it easy to see order of magnitude and to do math, since multiplying or dividing numbers translates to adding or subtracting exponents. For example, 4,500,000 becomes 4.5 × 10^6, and 0.000042 becomes 4.2 × 10^-5. It’s not a rounding method, not a unit conversion, and not limited to decimal fractions—the form represents any real number succinctly by adjusting the exponent.