If \(\frac{23}{2^5\cdot 5^9}\) is written as \(\frac{N}{10^9}\), what is \(N\)?

368

Core idea: write denominators with the same prime factors. Since \(10^9=2^9\cdot5^9\) and the given denominator is \(2^5\cdot5^9\), multiply denominator by \(2^4\) to get \(2^9\). Multiply the numerator by the same factor: \(N=23\times2^4=23\times16=368\). The closest distractor 184 corresponds to multiplying by \(2^3=8\) (one factor of 2 short), hence incorrect; 736 and 1472 result from using larger powers of 2. Exam tip: compare exponents of 2 and 5 in the denominator and multiply numerator/denominator to equalize them to powers of 10.

This is a Class 10 Mathematics question. Chapter: Real Numbers. Topic: Decimal expansion of rational numbers.