4 log 16log2 16 = 4, since 24 = 2 × 2 × 2 × 2 = 16. · Logarithms can also be negative: log 2 1 2 = − 1 {textstyle log _This free log calculator solves for the unknown portions of a logarithmic expression using base e, 2, 10, or any other desired base.!{frac 55kbet-93.pngThis free log calculator solves for the unknown portions of a logarithmic expression using base e, 2, 10, or any other desired base.}=This free log calculator solves for the unknown portions of a logarithmic expression using base e, 2, 10, or any other desired base.