https://www.khanacademy.org/math/ap-calculus-ab/ab-integration-new/ab-6-3/v/sigma-notation-sum 2021-06-30T17:32:38Z Summation notation Sigma, Σ, is the standard notation for writing long sums. Learn how it is used in this video. Sal Khan video https://cdn.kastatic.org/googleusercontent/AkUo89aMk-ZXH2KwZTUALeYknZORIY--gS_3ht52xZLOfQSEU8xfeGgm3Ohz0IeLeNCwAh0j_7M_tfBySGHDGA Summation notation Sigma, Σ, is the standard notation for writing long sums. Learn how it is used in this video. https://cdn.kastatic.org/ka-youtube-converted/5jwXThH6fg4.mp4/5jwXThH6fg4.mp4 267 Series https://www.khanacademy.org/math/integral-calculus/ic-series/ic-represent-func-as-series/v/writing-series-sigma-notation 2020-09-27T22:59:01Z Converting explicit series terms to summation notation Some sums are really long, but we can use sigma notation to write them in a shorthand way. See such an example here. Sal Khan video https://cdn.kastatic.org/googleusercontent/DnwmdpIJmJV_VSueuSPLMqdAXUgjRZzQmbr1Zm1eJCDYjZuu_fndndfYfUTZV54NX-WVRPaosA2_15NQz44_iMp_ZA Converting explicit series terms to summation notation Some sums are really long, but we can use sigma notation to write them in a shorthand way. See such an example here. https://cdn.kastatic.org/ka-youtube-converted/0DBDuNYsciY.mp4/0DBDuNYsciY.mp4 196 Series https://www.khanacademy.org/math/precalculus/x9e81a4f98389efdf:series/x9e81a4f98389efdf:geo-series-notation/e/evaluating-basic-sigma-notation 2025-03-01T15:52:37.13987578Z Summation notation intro Evaluate expressions that use sigma notation to make sure you understand what sigma notation means. Ben Stenhaug exercise https://www.khanacademy.org/math/ka-math-class-11/x0419e5b3b578592a:sequences-and-series-ncert-new/x0419e5b3b578592a:series/v/arithmetic-series-formula-indian-accent 2025-06-03T19:25:43.416794683Z Arithmetic series formula Learn how to write an arithmetic sequence in general terms, using a common difference d and a first term a. Next, we'll see that this formula is equivalent to multiplying the average of the first and last terms by the number of terms. Kalakrit (Dubbing) video https://cdn.kastatic.org/googleusercontent/ZCdwTudJg6e6n-P2gsaUborP4izvMsGo71pvEVlX9dNYWcLXcP7VHkWpn2grt4TUP1KoJLQP9NswyHBuBLSFTBw Arithmetic series formula Learn how to write an arithmetic sequence in general terms, using a common difference d and a first term a. Next, we'll see that this formula is equivalent to multiplying the average of the first and last terms by the number of terms. https://cdn.kastatic.org/ka-youtube-converted/o8NvEAmqCUs.mp4/o8NvEAmqCUs.mp4 466 Series https://www.khanacademy.org/math/ka-math-class-11/x0419e5b3b578592a:sequences-and-series-ncert-new/x0419e5b3b578592a:series/v/worked-example-fibonacci-sequence 2025-03-01T15:52:37.13987578Z Worked example - Fibonacci sequence Given the recursion formula for Fibonacci sequence, how do we generate the list of first few numbers. We first try playing with the recursion formula but then quickly realise the pattern. Every term is equal to the sum of the previous two. The question asks us to find the ratio of consecutive terms which means we briefly get to say hello to the golden ratio! Ashish Gupta video https://cdn.kastatic.org/googleusercontent/ZCdwTudJg6e6n-P2gsaUborP4izvMsGo71pvEVlX9dNYWcLXcP7VHkWpn2grt4TUP1KoJLQP9NswyHBuBLSFTBw Worked example - Fibonacci sequence Given the recursion formula for Fibonacci sequence, how do we generate the list of first few numbers. We first try playing with the recursion formula but then quickly realise the pattern. Every term is equal to the sum of the previous two. The question asks us to find the ratio of consecutive terms which means we briefly get to say hello to the golden ratio! https://cdn.kastatic.org/ka-youtube-converted/KaF0rEG8ySM.mp4/KaF0rEG8ySM.mp4 346 Series https://www.khanacademy.org/math/precalculus/x9e81a4f98389efdf:series/x9e81a4f98389efdf:arith-series/e/arithmetic_series 2025-03-01T15:52:37.13987578Z Arithmetic series Practice evaluating arithmetic series using the formula (n/2)⋅(a₁+aₙ). Ben Alpert exercise