Tính nhanh: 1,
\(\frac{423134x846267-423133}{846267x423133+423134}\)
2, 1919 x 18 - 1818 x 19
3, \(\frac{272727x28-282828x27}{1+2+3+.......+2014}\)
4, \(\frac{2929-101}{2x1919+404}\)
5, \(\frac{2}{7}-\frac{3}{8}+\frac{11}{7}+\frac{1}{3}+\frac{1}{7}-\frac{5}{8}\)