Using the Calculator Part I.

For a typical nongraphic calculator

N = (5.85 x 10⁹) x e^{(0.0136 x 20)}

Calculating the exponent (the number to which e is to be raised)

key in 0.0136
press the multiplication sign (x)
key in 20
press =

Press the e^x button
NOTE: On most calculators, e^x is labeled above a button that has another label such as ln. Some calculators require you to press the = key after the e^x.

press the multiplication sign (x)
enter the value 5.85 x 10⁹

enter 5.85
press the EE or EXP button
key in 9

press =