Area of circle = 50.265440
Circumference of circle =  25.132720
log(e) = 0.999999
log10(e) = 0.434294
log2(e) = 1.442694

5 examples with log2:
log2(2.000000) = 1.000000
log2(4.000000) = 2.000000
log2(8.000000) = 3.000000
log2(16.000000) = 4.000000
log2(32.000000) = 5.000000