Double logarithm (double x); It is based on e,

Log (10)/log (10) is enough to calculate the cardinality of 10.

The output is% f.

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# include & ltstdio.h & gt

# include & ltmath.h & gt

Master ()

{

Double b;

b = log( 100)/log( 10)；

printf("%f\n "，b)；

getchar()；

}

Output of 2.00000 should be enough.