How many buildings equaling 35x90 can I put on half acre?

Answer 1

A half acre is 21780 square feet.

As a mathematical problem, 35 x 90 = 3150 square feet x 6 = 18,900 square feet which is less than your lot.

As a zoning problem, we don't have nearly enough information as to whether six would be permissible.

Answer 2

It is not possible to answer the question because the measurement units used for the buildings are not specified. Also, the area does not provide sufficient information on the shape of the plot of land. In theory, half an acre could comprise a long narrow strip which is 726 feet long and 30 feet wide. So, if the buildings are 35 feet or 35 metres across, you will not get a single one to fit. If the plot is circular then there will be many gaps without building.

Finally, do the dimensions of the buildings include access space? If not, many of them will be unusable!