1-D Motion, calculating final velocity

[mncyapntsi]

Homework Statement

An electron is moving in a straight line with a velocity of 4x10^5 m/s. It enters a region 5.0 cm long where it undergoes an acceleration of
6.0x10^12 along the same straight line. (a) What is the electron’s velocity when it
emerges from this region? b) How long does the electron take to cross the region?

Relevant Equations

vf^2 = vi^2 + 2a(xf-xi)

Hello!
I have done this problem :
vf^2 = (4.0x10^5)^2 + 2(6.0x10^12)(5x10^-3)
so vf= sqrt((4.0x10^5)^2 + 2(6.0x10^12)(5x10^-3))
I get vf = 4.7 x 10^5 m/s
However, the textbook solutions says vf = 8.7x10^5 m/s.
Where did I go wrong?
Thank you for any help! :)

 

[hmmm27]

Well... how long is a cm, again ? In terms of metres, that is.

Does that get you any closer ?

 

[mncyapntsi]

Well... how long is a cm, again ? In terms of metres, that is.

Does that get you any closer ?

Oh no! Of course that changes the result haha.
Thank you so much for pointing that out :)