Better Farming Series 17  Groundnuts (FAO  INADES, 1977, 40 p.) 
Marking out the boundaries of the field 

19. To calculate the area of a field with right angles at the comers, multiply the length by the width of the field.
Example: a field is 100 metres long and 100 metres wide; its area is 100 x 100 = 10000 square metres (m^{2}).
A square metre is a square measuring 1 metre In length and 1 metre in width.
One hectare = 10 000 m^{2}.
Example: a field is 200 metres long and 50 metres wide; its surface is 200 x 50 = 10000 m^{2}.
It is also 1 hectare.
A field which is 71 metres long and 71 metres wide, has an area of 71 x 71 = 5041 m^{2}.
A field which is 100 metres long and 50 metres wide, has an area of 100 x 50 = 5 000 m^{2}.
These are both fields of half a hectare.
Before you put your stakes along the boundary of the field, you must ask permission to cultivate the field according to the local laws and customs.
You must ask permission to
cultivate the
field