Question 1 - Think & Reflect (Page 185) - Sum of the First n Natural Numbers - Chapter 8 - Predicting What Comes Next: Exploring Sequences & Progress

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Question 1 - Think & Reflect (Page 185) Can you use this formula to find 𝑆_20, 𝑆_50, 𝑆_1000? We know that Sum of first n natural numbers = 𝐒_𝐧=𝟏/𝟐 𝒏(𝒏+𝟏) To find values of 𝑆_20, 𝑆_50, 𝑆_1000, we just put values of n and solve Now, 𝑺_𝟐𝟎=𝟏/𝟐 × 𝟐𝟎 × (𝟐𝟎+𝟏) = 1/2 × 20 × 21 = 10 × 21 = 210 𝑺_𝟓𝟎=𝟏/𝟐 × 𝟓𝟎 × (𝟓𝟎+𝟏) = 1/2 × 50 × 51 = 25 × 51 = 1,275 𝑺_𝟏𝟎𝟎𝟎=𝟏/𝟐 × 𝟏𝟎𝟎𝟎 × (𝟏𝟎𝟎𝟎+𝟏) = 1/2 × 1000 × 1001 = 500 × 1001 = 5,00,500