Will somebody please help me? Thanks! Lots of Love!!!!!

The sum (S) of the first,n, positive integers(S=1+2+3+....+N) is S=n(n+1)over 2. Without using a calculator, determine the sum of the first 1000 multiples of 5: 5+10+15+........+5000.


The title of the page is solve a simpler problem!!!!!!

Notice first that 5+10+15+...+5000=5*(1+2+...+1000). Now we can use your formula to find:
5+10+15+...+5000=5*(1000*1001)/2=25025…

Hope this helps :)

Your formula is wrong you have s = n/2( n + 1) should be n/2(n + Last term)

a = first term, d = common difference, n number of terms, L= last term. s = sum

sum = n/2{a + L}

or s = n/2(2a + [n - 1]d)

your first term a = 5, n = 1000 and d = 5

Just evaluate using the second formula above