Tính nhanh: a, 11,2 - 7,6 + 8,8 - 2,37 b, 3,45 x 123 + 4 x 3,45 - 3,45 x 27

* Hướng dẫn giải

$$\begin{gathered} a, \\ \begin{array}{l}11,2-7,63+8,8-2,37=\underset{}{\underbrace{\left(11,2+8,8\right)}}-\underset{}{\underbrace{\left(7,63+2,37\right)}}\\ =20-10\\ =10\end{array} \\ b, \\ \begin{array}{l}3,45\times 123+4\times 3,45-3,45\times 27=3,45\times \left(123+4\right)-3,45\times 27\\ =3,45\times 127-3,45\times 27\\ =3,45\times \left(127-27\right)\\ =3,45\times 100\\ =345\end{array} \end{gathered}$$