Tính nhẩm:
\( \begin{array}{l}a) \; \;600 + 300 = \ \ \; \; \; \; \;900 - 300 = \ \ \; \; \; \; \;900 - 600 = \end{array} \) \( \begin{array}{l}b) \; \;600 + 60 = \ \ \; \; \; \;660 - 60 = \ \ \; \; \; \;660 - 600 = \end{array} \) \( \begin{array}{l}c) \; \;200 + 30 + 4 = \ \ \; \; \; \;500 + 70 + 5 = \ \ \; \; \; \;700 + 4 \; \; \; \; \; \; \; = \end{array} \)
A.\(\begin{array}{l}a)\,\,900\\\,\,\,\,\,\,600\\\,\,\,\,\,\,300\end{array}\) \(\begin{array}{l}b)\,\,660\\\,\,\,\,\,\,600\\\,\,\,\,\,\,60\end{array}\) \(\begin{array}{l}c)\,\,234\\\,\,\,\,\,\,575\\\,\,\,\,\,\,704\end{array}\)
B.\(\begin{array}{l}a)\,\,900\\\,\,\,\,\,\,600\\\,\,\,\,\,\,300\end{array}\) \(\begin{array}{l}b)\,\,606\\\,\,\,\,\,\,600\\\,\,\,\,\,\,66\end{array}\) \(\begin{array}{l}c)\,\,243\\\,\,\,\,\,\,575\\\,\,\,\,\,\,704\end{array}\)
C.\(\begin{array}{l}a)\,\,900\\\,\,\,\,\,\,630\\\,\,\,\,\,\,300\end{array}\) \(\begin{array}{l}b)\,\,660\\\,\,\,\,\,\,606\\\,\,\,\,\,\,60\end{array}\) \(\begin{array}{l}c)\,\,234\\\,\,\,\,\,\,557\\\,\,\,\,\,\,740\end{array}\)
D.\(\begin{array}{l}a)\,\,930\\\,\,\,\,\,\,600\\\,\,\,\,\,\,300\end{array}\) \(\begin{array}{l}b)\,\,606\\\,\,\,\,\,\,600\\\,\,\,\,\,\,300\end{array}\) \(\begin{array}{l}c)\,\,243\\\,\,\,\,\,\,557\\\,\,\,\,\,\,704\end{array}\)
