# Why two layers of matrix multiplication is needed in CBOW and Skip-gram model?

I found a nice tutorial here regarding CBOW and Skip-gram models for Word2Vec. I got the following doubt:

Why two layers of matrix multiplication is need for CBOW and SKIP-GRAM ? As multiplying a vector with a Matrix followed by another matrix can be written as multiplication by an equivalent single matrix.

$A = W$, $B = W'$. The number of elements in the matrix AB is $N^2$, while the number of elements in the matrix A + number of elements in the matrix B is $2VN$. (and $V \gg N$). Hence the use of two distinct matrices.