If the mean of a list of $1000$ consecutive odd integers is 0, what is the least number in the list?
If the mean = 0......then the sum of all the oods must = 0
The 500th positive odd = 2 (500) - 1 = 999
The 500th negative odd = 2 (-500) + 1 = -999 = the least number
+400 
