Tính nhanh.

Tính nhanh.

$\frac56+\frac{11}{12}+\frac{19}{20}+\frac{29}{30}+\frac{41}{42}+\frac{55}{56}+\frac{71}{72}+\frac{89}{90}$

Tính nhanh.

$\left(1-\frac34\right)\times\left(1-\frac37\right)\times\left(1-\frac{3}{10}\right)\times\left(1-\frac{3}{13}\right)\times\left(1-\frac{3}{16}\right)\times\left(1-\frac{3}{19}\right)$

Tính nhanh.

$\left(1-\frac12\right)\times\left(1-\frac13\right)\times\left(1-\frac14\right)\times\left(1-\frac15\right)\times\left(1-\frac16\right)\times\left(1-\frac17\right)$

Tính nhanh.

$\frac{1313}{1515}\times\frac{165165}{143143}\times\frac{424242}{151515}$

Tính bằng cách thuận tiện.

$M=\frac{3}{500}+\frac{8}{500}+\frac{13}{500}+\frac{18}{500}+\ldots+\frac{198}{500}$

Tính nhanh.

$A=\frac{\frac29+\frac{2}{19}+\frac{2}{129}}{\frac59+\frac{5}{19}+\frac{5}{129}}+\frac{\frac{3}{11}+\frac{3}{31}+\frac{3}{131}}{\frac{5}{11}+\frac{5}{31}+\frac{5}{131}}$