Making A Cell Equal To Another Cell But The Opposite Sign (±)

Hello all,

Say I have a cells A1 and A2 filled,

A1= -0.5
A2= 2

Is there a formula I could use in B1 and B2 so that the values of which would be the same but the opposite sign?

So For Example They would now be...

B1= 0.5
B2= -2

I am trying to do this for a vast column of data.

Thanks in advance for all help!!!