Here's an advanced one for rob with complex numbers:
i = i
That's obviously true. In other words
Sqrt( -1 ) = Sqrt( -1 )
Sqrt( -1/1 ) = Sqrt ( 1/-1 )
Sqrt(-1)/Sqrt(1)=Sqrt(1)/Sqrt(-1)
Sqrt(-1)=1/Sqrt(-1)
Now we multiply by i (or Sqrt(-1))
Sqrt(-1)Sqrt(-1)=1
-1 = 1
i = i
That's obviously true. In other words
Sqrt( -1 ) = Sqrt( -1 )
Sqrt( -1/1 ) = Sqrt ( 1/-1 )
Sqrt(-1)/Sqrt(1)=Sqrt(1)/Sqrt(-1)
Sqrt(-1)=1/Sqrt(-1)
Now we multiply by i (or Sqrt(-1))
Sqrt(-1)Sqrt(-1)=1
-1 = 1
The fool hath said in his heart, There is a God. They are corrupt, they have done abominable works, there is none that doeth good.
Psalm 14, KJV revised edition