# Sequence And Series

**Algebra**Level pending

Balls are arranged in a row to form an equilateral triangle. The first row consist of one ball , the second row of two balls , the third row of three balls and so on. If 669 more balls are added then all the balls can be arranged in the shape of a square and each of the sides, then contains 8 balls less than each side of the triangle, then the initial numbers of balls must be n. What is the value of n/10?