At Westonci.ca, we provide clear, reliable answers to all your questions. Join our vibrant community and get the solutions you need. Experience the convenience of finding accurate answers to your questions from knowledgeable experts on our platform. Experience the convenience of finding accurate answers to your questions from knowledgeable experts on our platform.

What is the sum of the first 50 natural numbers? How to solve it without adding 50 digits?

Sagot :

[tex]1+2+3+4+5+\dots+50\\\\1;\ 2;\ 3;\ 4;\ 5;\dots;50\ are\ the\ terms\ of\ a\ arithmetic\ sequence\\where\ a_1=1\ and\ d=1\\\\Sum:S_n=\frac{a_1+a_n}{2}\cdot n\\\\S_{50}=\frac{1+50}{2}\cdot50=51\cdot25=1275\leftarrow solution[/tex]
AL2006
Look at the first one and the last one:                  1 + 50 = 51
Look at the second one and the second-last one:  2 + 49 = 51
Look at the third one and the third-last one:           3 + 48 = 51

Every pair you construct in this way adds up to 51 .

There are ( 50/2 ) = 25 pairs.

They all add up to ( 25 pairs ) x ( 51 per pair ) = 1,275