It really depends on the kind of energy. Different kinds of energy are calculated in different ways.
This can usually be done algebraically.
by counting and calculating
You can use math in running by calculating how many miles or yards you have run.
Mental math! aka in ur head
by calculating their plays.
Calculating volume and surface area.
Joules
In the SI system the units are Joules. You can also use ftlbf (footpoundforce). For thermal energy use calories or BTU
In physics, the total amount of energy is measured in joules. The rate of energy use - joules/second - is the power, the unit is also known as watt. Electricity companies tend to use another measure for energy use: the kilowatt-hour (kWh), which of course is equal to 3.6 million joules.
To convert joules to megaelectronvolts (MeV), you can use the conversion factor 1 MeV = 1.60218 x 10^-13 joules. Simply divide the energy in joules by this conversion factor to get the equivalent energy in MeV.
To convert 1 cm-1 to joules, you can use the formula: Energy (in joules) (1 cm-1) x (1.986 x 10-23 J). This will give you the energy value in joules.
To convert energy in joules to wavenumbers, you can use the formula: Wavenumber (cm-1) Energy (Joules) / (Planck's constant x speed of light). This calculation helps relate the energy of a system to the corresponding wavenumber in spectroscopy.