Octonion
Numbers with eight dimensions are called octonions. You write them as
w = x0 + x1 i + x2 j + x3 k + x4 l + x5 il + x6 jl + x7 kl
and consists of the real numbers xa and the units i, j, k, l, il, jl, kl .
Explanation
When multiplying the units i, j, k, l, il, jl, kl the order plays a role.
1 i j k l il jl kl i −1 k −j il −l −kl jl j −k −1 i jl kl −l −il k j −i −1 kl −jl il −l l −il −jl −kl −1 i j k il l −kl jl −i −1 −k j jl kl l −il −j k −1 −i kl −jl il l −k −j i −1