Question

what is the sum when 1+2+3+4+5+6+...........is added till 250

Answer 1

This is natural numbers so use the formula n(n+1)/2

so n =250
therefore ....
   
 Sn=250(250+1)/2
     =(250*251)/2 
     =31375 

plz mark as d best...if it helped u..

Answer 2

1st method:
Sn (Sum of the 'n' numbers) = n/2 (2a+(n-1)d)
given, n=250, a (1st number) = 1, d ( common difference) = 1
then,
Sn = 250/2 (2(1)+(250-1)1)
     = 125(2+249)
     = 125(251)
     = 31375
therefore the sum of 1st 250 numbers = 31375

2nd Method:
Sn = n/2(a+l)
given, n=250, a=1, l (last term) = 250
Sn = 250/2 (1+250)
     = 125(251)
Sn = 31375

3d Method:
Sum of 1st 'n' natural numbers = n(n+1)/2 [since given n=250]
 = 250 (250+1)/2
 = 125(251)
 = 31375
therefore,  the sum of 1st 250 numbers = 31375