The special case of linear least squares is presented as an extremely useful estimation approach, in cases when the signal model can be written as a linear combination of known basis functions, with unknown weighting parameters. The linear least squares problem can be written as a matrix vector formulation and solved to yield the so-called normal equations. The video considers an example of estimating the Fourier coefficients of a signal modelled as a linear combinations of trigonometric functions. Finally, a numerical example is shown. The linear algebra manipulations are shown throughout in order to help the viewer manipulate similar types of equations, although a full geometric interpretation is not considered here.