CBSE · Class 6-12

Back to Arithmetic Progressions

Class 10 · Mathematics (Standard) · Unit 5: Arithmetic Progressions

Sums via Formulas

Lesson 6 of 6

Two special sums: (i) first

n

natural numbers

= n(n+1)/2

; (ii) first

n

odd numbers

= n^2

; (iii) first

n

multiples of

k

is

k\cdot n(n+1)/2

. Recognise these to save time.

AP in Real Life

Try the practice skills

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