# Find the Sum of All Integers Between 84 and 719, Which Are Multiples of 5. - Mathematics

Find the sum of all integers between 84 and 719, which are multiples of 5.

#### Solution

The integers between 84 and 719, which are multiples of 5 are:
85, 90...715
Here, we have:

$a = 85$

$d = 5$

$a_n = 715$

$\Rightarrow 85 + (n - 1)5 = 715$

$\Rightarrow 5n - 5 = 630$

$\Rightarrow n = 127$

$S_n = \frac{n}{2}\left[ 2a + (n - 1)d \right]$

$\Rightarrow S_{127} = \frac{127}{2}\left[ 2 \times 85 + (127 - 1)5 \right]$

$\Rightarrow S_{127} = \frac{127}{2}\left[ 800 \right] = 50800$

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#### APPEARS IN

RD Sharma Class 11 Mathematics Textbook
Chapter 19 Arithmetic Progression
Exercise 19.4 | Q 8 | Page 30