The selling price of one rock bolt (in Rs.) is given as, $S = (200 - 10n^{-0.5})$, where $n$ is the number of bolts produced. The manufacturing cost of rock bolts has a fixed component of Rs. 15000, and a variable component of Rs. 100 per bolt. The minimum break-even production, in number of rock bolts, is ______ (round off to 1 decimal place).