15,213 math problems. Every answer checked.

Free, no ads · 17 subjects · 152 topics

Problem of the day

Alternating fraction sums · Sequences and series · Earlier days

Sum of fractions with shared denominators

Find the value of (12+13+⋯+120)+(23+⋯+220)+⋯+(1819+1820)+1920\left(\frac{1}{2}+\frac{1}{3}+\cdots+\frac{1}{20}\right)+\left(\frac{2}{3}+\cdots+\frac{2}{20}\right)+\cdots+\left(\frac{18}{19}+\frac{18}{20}\right)+\frac{19}{20}.

Sign in to save your progress.

Start solving