1+2+3+······+98+99+100=?

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 1+2+3+4·······+98+99等于多少 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+2+3+······+98+99+100=? 计算1-2+3-4+5-6+······-98+99= 1+2+3+······+95+96+97+98+99=? 急·····················1+2+3+...+999=? 1 2 3 4 ·····7 ·······10 ········?1 3 5 7 ·····?······?··········290 1 4 9 ·····?······?··········? 巧算：100+99-98-97+96+95-·····+4+3-2-1 100+99-98-97+96+95+·······+4+3-2-1怎么做? 1/100+2/100+3/100·······98/100+99/100怎样算? 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= (1+3+5+7+·····+99+101)—(2+4+6+8+····+98+100) 怎样快速算出1+2+3+4+5······+98+99+100? 1x2+2x3+3x4+4x5+······98x99+99x100=? 1+2-3+4+5-6······+97+98-99的解题方法是巧算快 计算：1-100+2-99+3-98+···+98-3+99-2+100-1