68×28+31×28+28怎么简便计算?还有[(12+36)×20]×(27+38)
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![68×28+31×28+28怎么简便计算?还有[(12+36)×20]×(27+38)](/uploads/image/z/1742918-14-8.jpg?t=68%C3%9728%EF%BC%8B31%C3%9728%EF%BC%8B28%E6%80%8E%E4%B9%88%E7%AE%80%E4%BE%BF%E8%AE%A1%E7%AE%97%3F%E8%BF%98%E6%9C%89%5B%2812%2B36%29%C3%9720%5D%C3%97%2827%2B38%29)
68×28+31×28+28怎么简便计算?还有[(12+36)×20]×(27+38)
68×28+31×28+28怎么简便计算?
还有[(12+36)×20]×(27+38)
68×28+31×28+28怎么简便计算?还有[(12+36)×20]×(27+38)
68×28+31×28+28
=(68+31+1)×28
=100×28=2800
[(12+36)×20]×(27+38)
=48×20×65
=48×13×(20×5)
=624×100=62400
28×(68+31+1)=2800
68×28+31×28+28
=68×28+31×28+1×28
=(68+31+1)×28
=100×28=2800
[(12+36)×20]×(27+38)
=48×20×65
=48×20×5×13
=48×13×(20×5)
=(50×13-2×13)×(20×5)
=624×100=62400