Big is a simple, immutable wrapper around Go's built-in *big.Float type designed to offer a more user-friendly API and immutability guarantees at the cost of some runtime performance.
Because Big wraps *big.Float, it uses arbitrary-precision binary floating-point arithmetic. It is not a fixed-point decimal or money library. If you need decimal-exact financial arithmetic, use a decimal package with explicit scale and rounding semantics.
Usage is dead simple:
dec := big.NewDecimal(1.24)
addend := big.NewDecimal(3.14)
dec.Add(addend).String() // prints "4.38"