牛津深圳初中英語七上unit4theworldofnumbers課件(存儲版)
【正文】 . 2. Which system of numbers did the Indians invented? The system of . 3. What invention helped people write in big numbers? The invention of . counted in tens 1 to 9 zero the first 2 parts. A small machine that uses electronic power to do calculations. An electronic calculator A very powerful machine for doing calculation. A puter A calculating machine with wires and beads. An abacus Calculating machines 1. Features (特點） : fast accurate 2. What does beads on the wires stand for? 3. Figure: Formulas thousands hundreds tens ones an abacus wires beads 5 7 2 4 1 : 5724 0+1=？ A: What can an electronic calculator do?
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