bc command

# To run calculator in interactive mode using the standard math library:
bc -l

# To calculate the result of an expression:
bc <<< "(1 + 2) * 2 ^ 2"

# To calculate expression and force number of decimal places to 10:
bc <<< "scale=10; 5 / 3"

# To calculate expression with sine and cosine using mathlib:
bc -l <<< "s(1) + c(1)"