>>>>>On the 1st day of Xmas, my true love gave to me:
>>>>>1 item
>>>>>On the 2nd day of Xmas, my true love gave to me:
>>>>>2 items + 1 item
>>>>>On the 3rd day of Xmas, my true love gave to me:
>>>>>3 items + 2 items + 1 item
>>>>>.
>>>>>.
>>>>>On the n-1 day of Xmas, my true love gave to me:
>>>>>n-1 items + n-2 items + ... + 1 item
>>>>>On the nth day of Xmas, my true love gave to me:
>>>>>n items + n-1 items + ... + 1 item
>>>>>
>>>>>How many total items did my true love give to me, as a function of n?
>>>>
>>>>Number of gifts = gifts(n)
>>>>
>>>>
>>>>FUNCTION gifts(n)
>>>>lnReturn = 0
>>>>FOR I = 1 TO n
>>>> FOR H = 1 TO I
>>>> lnReturn = lnReturn + H
>>>> ENDFOR
>>>>ENDFOR
>>>>RETURN lnReturn
>>>>
>>>>
>>>>not arithmetic, but it works
>>>
>>>Er, yes, but there is an elegant mathematical solution that even a computer would like! (no looping involved)
>>
>>
>>Maybe it can be : Gifts = (n+1) * (n/2) ??
>
>Um, no, we've seen that one earlier...that's not the cumulative sum for all the days, that's only one day...

Sum=(N^3)/6+(N^2)/2+N/3
If this is right, I will send you bill ::)