8i^-6?
Some background: i2 = -1 i4 = 1 i8 = (i4) · (i4) = 1 · 1 = 1
8 · (i-6)
Multiply by i8 (which is just 1): 8 · (i-6) · i8 = 8 · i2 = 8 · -1 = -8