However, I contend that there are advantages to memorizing a few important equations and numbers. These reasons include the following:

- You may work faster since you will not need to constantly reference those equations.
- You may mentally check your work to ensure that the numbers are correct.
- You may mentally approximate the solutions to certain calculations if you don't have access to reference material. I remember reading once how Feynman would challenge mathematicians by approximating powers of numbers in his head by knowing the natural logarithms of 2 and 10.
- You may impress the ladies with your abilities (not guaranteed).

- The binomial expansion
- The Taylor expansion
- The power series representation of
*e* - The speed of light in vacuum and the impedance of free space (about 377 Ohms)
- The refractive index of common glass (~1.5) and water (~1.33)
- Boltzmann's constant and the thermal energy at 300 K (4.14 Joules) and thermal voltage at 300 K 0.026 eV)

- Stirling's approximation
- The Krebs cycle (a biologist once told me that many ideas in molecular biology come back to this)

*Addendum*: Not memorizing the basics is a mistake to avoid in physics according to this Back Page of APS News.