1*3+2*3+3*3+........+20*3 – InterviewSolution

1.	13+23+33+........+203
Answer» remove 3 as common3(1+2+3+..20)now 1+2+..20 forms an aphenceS=n/2(a+l)dS=20/2(1+20)1S=10(21)=210hence total sum will be 2103=630

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