1+11+111+2+····+99+999给我一个简便算法?

1+11+111+2+····+99+999给我一个简便算法? 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 简算:1999+199·9+19·99+1·999+2·111 计算1-3+5-7+9-11+··········+97-99= 1 2 3 4 ·····7 ·······10 ········?1 3 5 7 ·····?······?··········290 1 4 9 ·····?······?··········? 1+2···+99 这几道奥数题谁会,求2014在哪一行那一列 1 2 3 4 5 10 9 8 7 6 11 12 13 14 15 20 19 18 17 16 求2014哪一行那一列 1 2 3 4 5 6 7 8 9 ···· ····· ·························· 1+3+5+7+9+11+13+15+17+··· ···+93+95+97+99=? 计算1-2+3+4-5+6+7-8+9+10-11+12+······+97-98+99 问11111········111（100个1）除以9等于多少做法 把自然数从1开始,排列成下表：1 2 4 7 11 16······ 3 5 8 12 17······ 6 9 13 18·····把自然数从1开始,排列成下表：1 2 4 7 11 16······3 5 8 12 17······6 9 13 18······10 14 19······15 20·· 1+2+3+4·······+98+99等于多少 正整数按图的规律排列,请写出第二十行,第二十一列的数 列 行 1 2 5 10 17 4 3 61118 9 8 7 12 19 急列 1 2 3 4 5行 1 2 5 10 17······················ 4 3 6 11 18······················9 1+2+3+4+5+6+7+8+9······+99=?1 1-2+3-4+5-6+7-8+9······+99-100 观察下列三角形数表其中从第二行起每行的每一个数为其肩膀上两树之和则该表的最后一个数是?1 2 3 4 5 6 7 8················ 97 98 99 100 3 5 7·························· 1*3*5*7*9*······*99=?注：*表示乘号,······表示省略号. -1-3-5-7-9······-97-99怎么计算