Convert from X unit to metre

Unit Definition (X unit)
The X-unit (symbol xu) is a unit of length formerly used to measure the wavelength of X-rays and gamma rays. The X-unit is approximately 1.0021×10-13 metre. Defined by the Swedish physicist Karl Manne Georg Siegbahn (1886-1978) in 1925, the X-unit could not at that time be measured directly; the definition was instead made in terms of the spacing between planes of the calcite crystals used in the measuring apparatus.

Unit Definition (metre)
The meter is the basic unit of length adopted under the Systeme International d'Unites (approximately 1.094 yards). The meter is also the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second by definition