In this video I explain in great detail and STEP by STEP why the formula for the sum of an arithmetic series is S_n=(n/2)*[2a+(n-1)d]. My goal here on Youtube is to help you understand why certain mathematical formulas exist before you begin working with them. This, I believe, will give you a deeper understanding of mathematical principles. If this video is a bit too complicated for you, then I would suggest watching the video below first - then returning here at a later date: https://youtu.be/3p87wDxR0LM To support my work, follow me on Instagram here: https://www.instagram.com/tiago_hands/ For mathematics proofs on Instagram, follow this page: https://www.instagram.com/mathematics.proofs/ If you'd like to donate to my project, you can do so through here: https://flattr.com/@tiago_hands Thanks for watching! ... https://www.youtube.com/watch?v=6U_qxdBGIwU

In this video I demonstrate how you can sum up values associated with multiple name - all at once (Open Office 4). This video may be useful to bookkeepers, accountants, scientists, engineers and mathematicians. If you like this video, do not forget to subscribe to my Youtube channel. You can also follow me at: https://www.instagram.com/tiago_hands ... https://www.youtube.com/watch?v=WFst-T997K4