Returns a string representation of the BigDecimal in exponential notation
rounded to the specified number of digits after the decimal point.
toExponential(digits, roundingMode)
digits
The number of digits after the decimal point.
roundingMode optional
A string specifying the rounding mode: "floor", "ceiling", "down", "up", "half-even", "half-up". Defaults to "half-up".
A string representing the value in exponential notation.
123.4567m.toExponential(1)
"1.2e+2"
123.4567m.toExponential(3)
"1.235e+2"
123.4567m.toExponential(3, "down")
"1.234e+2"