Latest Maths Aptitude Question SOLUTION: 1*2+2*3+3*4+-----------+99*100 1) 330033 2)300033 3)330000 4)333000 5)330003 6)333300

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1*2+2*3+3*4+-----------+99*100

1) 330033
2)300033
3)330000
4)333000
5)330003
6)333300

Asked In Maths munagala vasu (9 years ago)

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RAKESH  (9 years ago)

6) 333300
tn = n*(n+1)
given exp is = Σtn = Σ n*(n+1) [n=1 to n=99]

= Σ(n^2+n) = n*(n+1)*(2n+1)/ 6 + n*(n+1)/2
on solving, = n*(n+1)*(n+2) / 3

put n=99, we get reqd sum = 99*100*101/3 = 333300

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munagala vasu  (9 years ago)

ans is 6) 333300

explanation : 1(1+1)+2(2+1)+3(3+1)-------99(99+1)

=> ((1*1)+(2*2)+(3*3)+-----(99*99))+(1+2+3+-------99)

=> (99*100*199)/6 + 4950

=> 333300

OR

We can solve frm formula

tn = n*(n+1)
given exp is = Σtn = Σ n*(n+1) [n=1 to n=99]

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