JAVASCRIPT

Round Decimal

Number((2.935).toFixed(2)) //2.94
Number((12.349345).toFixed(4)) //12.2493
Number((2.5398).toFixed(3)) //2.540

Number((1.005).toFixed(2)) //outputs 1 instead of 1.01
Number((1.555).toFixed(2)) //outputs 1.55 instead of 1.56

Round to 2 decimal places

function roundToTwo(num) {
    return +(Math.round(num + "e+2")  + "e-2");
}
console.log(roundToTwo(2.005));

round to 2 decimal places

a = 2.154327
a_2_decimal = "{:.2f}".format(a)

round to 0 decimal

df.astype(int)
          <=35  >35
Cut-off            
Calcium      0    1
Copper       1    0
Helium       0    8
Hydrogen     0    1