Tính nhẩm:\(\begin{array}{l}a)\;\;600 + 300 = \\\;...

Câu hỏi: 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 \(\begin{array}{l}a)\,\,930\\\,\,\,\,\,\,600\\\,\,\,\,\,\,300\end{array}\)                          \(\begin{array}{l}b)\,\,606\\\,\,\,\,\,\,600\\\,\,\,\,\,\,300\end{array}\)                        \(\begin{array}{l}c)\,\,243\\\,\,\,\,\,\,557\\\,\,\,\,\,\,704\end{array}\)