Problem in the Defination of electon's wavelength

[soopo]

Given:
$$\lambda = h / (mv)$$, whehere lambda is the wavelength of electron, h Planck's constant, m the rest mass of electron and v the speed of electron.

Problem:
Does electron has a mass? I know it has a rest mass and thus contain energy. This problem is perhaps a defination problem.

 

[Doc Al]

Sure the electron has a mass. (What would make you think otherwise?)

 

[Gnosis]

electron mass = 9.109382 x 10 to the -31st power (in kg)