Question 619384
  <pre><font face = "Tohoma" size = 3 color = "indigo"><b> 
Hi,
finding the sum  of sequence: 41+42+43+44+.....+118
Arithmetic Sequence with {{{a[1] = 41}}} and d = 1
{{{a[n]=a[1]+(n-1)*d}}}
{{{a[n]= 41+(n-1)*1 = 118}}}
     n = 118-41 + 1
     n = 78
{{{S[n]=(n/2)(2*a[1]+ (n-1)d)}}}
{{{S[78]=(78/2)(2*41+ (77)1)}}}
{{{S[78]=(39)(159)}}}
{{{S[78]= 6201}}}