Source: The Math League
http://www.mathleague.com
A run of numbers is a collection of whole numbers with no gaps in it, such as 2, 3, 4; but not 5, 6, 8, 9 because 7 is missing. 2, 3, 3 is not a run because 3 is repeated. Practically all numbers can be written as a sum of a run (we will not allow a run to start at 0). For example, 9 = 2 + 3 + 4, 10 = 1 + 2 + 3 + 4, 11 = 5 + 6 and we will can them RUNSUMS. Note that there is no RUNSUM of 4 or 8.
2A. What is the smallest number that is a sum of a run of 3 numbers?
2B. What is the smallest number that is a sum of a run of 4 numbers?
2C. What is the smallest number that is a sum of a run of 5 numbers?
2D. What is the smallest number that is a sum of a run of 10 numbers?
2E. What is the smallest number that is a sum of a run of 100 numbers?
2F. What is the smallest number that is a sum of a run of 'n' numbers?
Source: The Math Forum
http://forum.swarthmore.edu/midpow/solutions/solution.ehtml?puzzle=18
Don Braffitt