[Guntitat Gun]

${=\frac{1}{6}-\frac{1}{7}+\frac{1}{7}-\frac{1}{8}+\cdots+\frac{1}{10}-\frac{1}{11}}$
${=\frac{1}{6}-\frac{1}{11}}$
${=\frac{5}{66}}$

ตอบ ${\frac{5}{66}}$