# Count 'em Slopes (Count 'em All 17!)

Discrete Mathematics Level 5

A slope grid is a grid that is made by diagonally slicing a regular grid in half, for example, the figure below shows 4 slope grids with dimensions $$1\times1$$, $$2\times 2$$, $$3\times3$$, $$4\times4$$ respectively.

Count the total number of quadrilaterals in a $$30\times30$$ slope grid (that is, when $$a=30$$).

Clarification: A quadrilateral is a polygon that has 4 sides.

×