# Calculating the smallest power of 10 a number is less than

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Is there a calculation whereby you can calculate the smallest power of 10 that a number (variable) is less than. For example x = 392.41253 y = 0.39241253 = x / (10 ^ 3). using C++ this can be calculated
double x = 392.41253;
unsigned int p = 0;
for (double a = x; a > 0.0; p ++)
a /= 10.0;
y = x / pow(10.0, p);

p = 3, giving the correct answer. However, is there a simpler way to figure out what p will be ? (using a calculation as opposed to a loop)

log base 10?

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Haha! Its been many years since I used that, thanks. Forgetfullness.