Adv
Rajan@2021
  • 0
Guru

Find the sum of all 3 digit natural numbers which are divisible by 7.

  • 0

One of the most important question from ML Aggarwal from Arithmetic Progression is to find the sum of all 3 digit natural numbers which are divisible by 7.

Arithmetic Progression chapter 9 question no 21 ii

Share

1 Answer

  1. All three-digit natural numbers which are divisible by 7 are

    105,112,119,126,...,994 which are in AP with a=105,d=7,l=994
    Let the number of these terms be n. Then,
    an=994
    a+(n1)d=994
    105+(n1)×7=994
    n=128
    Now, Sn=2n(a+l)

    Sn=2128(105+994)=70336.

    • 0
Leave an answer

Leave an answer

Browse

Choose from here the video type.

Put Video ID here: https://www.youtube.com/watch?v=sdUUx5FdySs Ex: "sdUUx5FdySs".

Captcha Click on image to update the captcha.

Related Questions