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Find the sum of all positive integers less than 1000 ending in 3 or 4 or 5.

 Aug 13, 2024
 #1
avatar+1926 
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First, let's note that

\(3 + 4 + 5 = 3 *4\)

\(13 + 14 + 15 = 3 * 14\)

 

This pattern will keep going. Thus, we just have

\(3 [ 4 + 14 + 24 + ....... + 994 ]\)

 

No. of terms =  100

 

Thus, our final answer is

\(3 [ 994 + 4 ] [ 100 / 2 ] = 149,700\)

 

Thanks! :)

 Aug 13, 2024
edited by NotThatSmart  Aug 13, 2024

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