4000-1-2-3-···-77-78=?

4000-1-2-3-···-77-78=? 5000-1-2-3-······-76-77-78=? 500-1-2-3-········-76-77-78.怎么算?要巧算. 急·····················1+2+3+...+999=? 1 2 3 4 ·····7 ·······10 ········?1 3 5 7 ·····?······?··········290 1 4 9 ·····?······?··········? 1+2+3+4+······+78+79+801/2+1/6+1/12+1/20+······+1/72+1/90100-99+98-97+96-······+4-3+2-11000-1-2-3-4-······-78-79-801/15+2/15+······+13/15+14/15注：例 1/15 就是 十五分之一 1+2++3+··········+10000= 8+11+14+17+20+·······+305 数学计算题.呜呜呜1+2+3+4+···················+98+99+100+99+98+···············+3+2+1 把这些数字由基数词变成序数词1·2·3·4·5·6·7·8·9·10·11·12·20·30·40·50·60·70·80·90·21·35·78 秦始皇和汉武帝各自的功劳是?（用1·······2·······3··········来说） 变态数学题·······方程一道············x+2y+3z=1x=y+12x+3y+5z=2方程组············要过程············我解了之后总觉得无解····· 55*66+66*77+77*78+88*89简便运算要过程,急············ 俗语和名句的填空1······,自知之明.2······,行必果.3工欲善其事,······.4临渊羡鱼,······.5非学无以广才,······.6······,福兮祸之所伏.7项庄舞剑,······.8······,人以群 已知三个角1,2,3满足：1与2互补,2与3互余,试求1-3的大小!································· 2[4/3y—（2/3y—1/2）]=3/4y急·································!1 证明1·3·5·····(2n-1)/2·4·6·····2n 1/3+2/3=1,但0.333···+0.666···=0.999···,为神马?额······谁能解释一下······ 将下列每个3*3正方形内的九格以及横竖九格均填入一至九的数字,且不重复.· 8 9 · 2 ··1··· 1 ··· 3······· 6 7········· 8 2·········5 ···· 7 ··············· 9 8 ····7 ·