Grade 5

The convenient sum

Nine improper fractions, one neat trick -- every term hides a whole one, and what is left folds up on itself.

1
Calculate conveniently
Calculate the sum in a convenient way: $\frac{3}{2} + \frac{7}{6} + \frac{13}{12} + \frac{21}{20} + \cdots + \frac{73}{72} + \frac{91}{90}.$