CameraIcon
CameraIcon
SearchIcon
MyQuestionIcon


Question

Find the sum of first seven numbers which are multiples of 2 as well as of 9.


Solution

Clearly, the first seven numbers which are multiples of 2, as well as 9, are $$18,36,54.....126. $$
This is an AP with first term $$a=18$$ and last term $$l=126$$. 
Let $$S_n$$ be the sum of n terms of an AP. 
Then, $$S_n=\cfrac n2(a+l)$$
Putting $$a=18,n=7$$ and $$l=126$$ in $$S_n$$, we get
$$S_7=\cfrac 72(18+126) \Rightarrow S_7=\cfrac 72(144) \Rightarrow S_7=504$$

Mathematics

Suggest Corrections
thumbs-up
 
0


similar_icon
Similar questions
View More


similar_icon
People also searched for
View More



footer-image