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Find the sum to n terms of each of the series 1)1*2+2*3+3*4+4*5........ 2)1*2*3+2*3*4+3*4*5+....... 3)3*1*1+5*2*2+7*3*3+...... 4)1/1*2+1/2*3+1/3*4+....... 5)5*5+6*6+7*7+.....+20*20 6)3*8+6*11+9*14+...... 7)1*1+(1*1+2*2)+(1*1+2*2+3*3)+..... well it will be easy for me to understand if you give explanation too. have a nice day !