EDG nếu đề laf thế này thì
\(B=\frac{1}{1.2}+\frac{1}{3.4}+\frac{1}{5.6}+...+\frac{1}{99.100}\)
\(B=\frac{1}{2}+\left(\frac{1}{3.4}+\frac{1}{5.6}+...+\frac{1}{99.100}\right)\)
\(B=\frac{1}{2}+\left(\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+....+\frac{1}{99}-\frac{1}{100}\right)\)
\(B=\frac{1}{2}+\left(\frac{1}{3}-\frac{1}{100}\right)\)
\(B=\frac{1}{2}+\frac{97}{300}\)
\(B=\frac{247}{300}\)