const x = 3800.5; console.log(x.toExponential(4)); // 3.8005e+3 console.log(x.toExponential(3)); // 3.801e+3 console.log(x.toExponential(2)); // 3.80e+3 console.log(x.toExponential(1)); // 3.8e+3 console.log(x.toExponential(0)); // 4e+3