Fixed spelling error, reported by Hans Persson. (Bug 989).

README

@@ -15,7 +15,7 @@ smallest numbers.  The result is inserted in the proper place among
 the remaining numbers, and the two smallest numbers are added once
 again.  The process repeats until only one number remains: the sum.
 
-As long as you only have positiv numbers, this algorithm should work
+As long as you only have positive numbers, this algorithm should work
 fairly well.  If you have negative numbers, it will work just as well,
 since the program sorts the numbers based on the absolute value of the
 numbers.  If, however, you have both positive and negative numbers,