Question

Sum of 15 numbers and sum of 25 is given find sum fo first 45 numbers

Answer 1

Answer:

Step-by-step explanation:

1+2+3+…….+45 , here first term a = 1 , last term l= 45 , total number of terms n = 45 , so the sum S = n/2 {a+l} = 45/2 {1+45}= 45*23 =1035

We can also conclude the same result with the formula of the sum of the first n natural number , i.e

S = n(n+1)/2 = 45(45+1)/2 =45*23=1035