Arithmetic progression · समांतर श्रेढ़ी

3, 7, 11, 15 … next? 20th term? Sum of 20 terms?

Arithmetic progression games

A list of numbers where each term is the previous one plus a fixed common difference d: 3, 7, 11, 15, … (d = 4).

nth term: aₙ = a + (n − 1)d
Sum of first n terms: Sₙ = n/2 [2a + (n − 1)d] = n/2 (first term + last term)
Example: 1 + 2 + … + 100 = 100/2 × (1 + 100) = 5050 (Gauss's trick).

For Class 9 and 10 (NCERT Ganita Manjari 9, “Sequences and Progressions”; Class 10 Arithmetic Progressions). Answers are computed by a program.

A one-page chart to stick on the wall, and a worksheet to practise.

A list of numbers where each term is the previous one plus a fixed common difference d: 3, 7, 11, 15, … (d = 4).

nth term: aₙ = a + (n − 1)d
Sum of first n terms: Sₙ = n/2 [2a + (n − 1)d] = n/2 (first term + last term)
Example: 1 + 2 + … + 100 = 100/2 × (1 + 100) = 5050 (Gauss's trick).

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Name: ____________________ Class: ______ Date: __________

1. Find d and the next two terms: 5, 9, 13, … ____

2. Find the 25th term of 2, 7, 12, … ____

3. Sum of the first 30 odd numbers = ____

4. Which term of 3, 8, 13, … is 78? ____

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