巧算1*2+2*3+3*4+······+49*50=?
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巧算1*2+2*3+3*4+······+49*50=?
根据公式n(n+1)=n^2+n,
1*2+2*3+3*4·······+49*50
=49*50*99/6+49*50/2
=41650.
1*2+2*3+3*4·······+49*50
=49*50*99/6+49*50/2
=41650.
1×2×3×4······×48×49×50=?
计算1+(2+3)-(4+5)+(6+7)-(8+9)······-(48+49)+50=
50+49-48-47+46+45-44-43+······-4-3+2+1=?
1+2++3+··········+10000=
1+3+5+···45+47+49+50+51+53+55+···+95+97+99-2-4-6-···-96-98-1
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,······.
1+1/1+2+1/1+2+3······+1/1+2+3+4+5+6······+46+47+48+49+50得多少?
(1-2)×(2-3)×(3-4)×······×(19-20)=
1\(2\3)\(3\4)······\(18\19)\(19\20)=
1+2+3+4+5+6······38+39=?
1+2+3+4··· ···+78+79=?
计算1-2+3-4+5-6+······-98+99=