<p>On the Math SAT or more generally the SAT does the notation 'log(x)' refer to the base 10 logarithm or the natural logarithm? I assumed it was the natural logarithm because that is how I have always seen it and how mathematica etc displays it, but I got a problem wrong on one of Barron's test where I guess it was supposed to denote the base 10 logarithm. So which is it?</p>
<p>Base 10. If it were natural log, it would be ln(x) with base e.</p>