Finding Sums in the Middle - Chapter 8 - Predicting What Comes Next: Exploring Sequences & Progress

Last updated at August 14, 2026 by

Finding Sums in the Middle - Ganita Manjari Class 9 Chapter 8 Maths - Sum of the First n Natural Numbers

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Finding Sums in the Middle How do we find this sum 25 + 26 + 27 + ... + 58 ? For this we write 25 + 26 + 27 + ... + 58 = (1 + 2 + 3 + 4 + โ€ฆ. + 58) โ€“ (1 + 2 + 3 + 4 + โ€ฆ 24) = ๐‘†_58โˆ’๐‘†_24 = ๐Ÿ/๐Ÿ ร— ๐Ÿ“๐Ÿ– ร— ๐Ÿ“๐Ÿ—โˆ’๐Ÿ/๐Ÿ ร— ๐Ÿ๐Ÿ’ ร— ๐Ÿ๐Ÿ“ = 29 ร— 59 โ€“ 12 ร— 25 = 1711 โ€“ 300 = 1411

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