Răspunsuri

2014-10-22T19:37:24+03:00
(1+2+3+4+....+20)=20x21:2=10x21=210
Multumesc
Ma puteti ajuta si pe mine?
cu ce?
(1+2+3+4+...+20)=20x21:2=10x21=210
2014-10-22T19:39:28+03:00
Sunt doua metode 1+20+2+19+3+18+4+17+5+16+6+15+7+14+8+13+9+12+10+11= 21+21+21+21+21+21+21+21+21+21= 41+41+41+41+41=82+82+41=164+41=205
si a doua e prin simplificare