动手学数学之九(位数问题)_四年级-查字典奥数网
动手学数学之九(位数问题)
2009-03-09 17:16:09
标签:速算与巧算
123456789 987654321
123456780 087654321
123456700 007654321
123456000 000654321
123450000 000054321
123400000 000004321
123000000 000000321
120000000 000000021
100000000 000000001
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_________ _________
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