\(1+\dfrac{2}{3}=\dfrac{3}{3}+\dfrac{2}{3}=\dfrac{5}{3}\)
\(1-\dfrac{2}{3}=\dfrac{3}{3}-\dfrac{2}{3}=\dfrac{1}{3}\)
\(1\times\dfrac{2}{3}=\dfrac{2}{3}\)
\(1\div\dfrac{2}{3}=1\times\dfrac{3}{2}=\dfrac{3}{2}\)
\(1+\dfrac{2}{3}=\dfrac{3}{3}+\dfrac{2}{3}=\dfrac{3+2}{3}=\dfrac{5}{3}\)
\(1-\dfrac{2}{3}=\dfrac{3}{3}-\dfrac{2}{3}=\dfrac{3-2}{3}=\dfrac{1}{3}\)
\(1\cdot\dfrac{2}{3}=\dfrac{2}{3}\)
\(1:\dfrac{2}{3}=1\cdot\dfrac{3}{2}=\dfrac{3}{2}\)
(Chú ý: Dấu \(\cdot\) là phép nhân, lên lớp 6 sẽ học, tạm thời viết x)