Best Guess

Best Guess is a spell that provides the caster with an instant and highly accurate
estimate of the number of persons or objects in a group.
The spell's area of effect is one group of a general class of objects. All objects of the
group must be within spell range and the group as a whole must be visible to the caster.
The wizard need not see every individual in the group, merely the general limits of the
group's size and area. For example, a wizard on a hill could look down on a forest and
estimate the number of trees in all or part of it. He could not get an estimate of the
number of goblins within the forest, however, since the group as a whole (the goblins) is
concealed from sight.
The estimate generated is accurate to the largest factor of ten (rounded up). For
example, if Best Guess were cast on a group of 439 horsemen, the estimate would
be 400. If there were 2,670 horsemen, the spell would estimate 3,000. If there were 37
horsemen, the answer would be 40. Clearly, using the spell on small groups (especially
those with fewer than 10 members) is pointless.
Best Guess can be used to quickly estimate the size of treasure hoards and army
units. It is particularly popular with moneylenders and generals.