The Druly lane theatre has 17 seats in the first row and 26 rows in all. Each successive row contains one additional seat. How many seats are in the theatre?
>>8513795
bout tree fiddy
767
>>8513800
You're a wiz bro. Thanks. I was seriously about to pull out a separate scratch paper and do 17+18+19... 26 times. I tried Gauss and had no success.
>>8513809
The first row has 17 seats and the last row will have 17+25=42 seats. Then you do (17+42)*13 to get 767
17*26 + 26* 12.5