Calculate logarithm of a number to any base:
* Use e for scientific notation. E.g: 5e3, 4e-8, 1.45e12
When:
b y = x
Then the base b logarithm of a number x:
logb x = y
In order to calculate log-1(y) on the calculator, enter the base b (10 is the default value, enter e for e constant), enter the logarithm value y and press the = or calculate button:
When
y = logb x
The anti logarithm (or inverse logarithm) is calculated by raising the base b to the logarithm y:
x = logb-1(y) = b y
Logarithm rules
Logarithm product rule
logb(x × y) = logb(x) + logb(y)
Logarithm quotient rule
logb(x / y) = logb(x) - logb(y)
Logarithm power rule
logb(x y) = y × logb(x)
Logarithm base switch rule
logb(c) = 1 / logc(b)
Logarithm change of base rule
logb(x) = logc(x) / logc(b)