# Monthly Archives: March 2015

## An identity

The following problem is apparently a bonus question for 13 year olds at a local girls school: Evaluate the sum $\displaystyle \frac{1-\frac{1}{2}+\frac{1}{3}-\frac{1}{4} + \cdots + \frac{1}{99} – \frac{1}{100}}{\frac{1}{1+101}+ \frac{1}{2+102} + \cdots + \frac{1}{50+150}}.$ It’s not that easy if … Continue reading