+0  
 
0
4
1
avatar+415 

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

 May 28, 2024

Best Answer 

 #1
avatar+1280 
+1

To complete this problem, we must make an important observation.

 

NOTE: 

\(3 + 4 + 5 = 3 *4 \\ 13 + 14 + 15 = 3 * 14\)

 

Now, we just have to figure out \(3 [ 4 + 14 + 24 + ....... + 994 ] = \)

 

There are 100 terms in the sequence, so we have

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

 

Thanks! :)

 May 28, 2024
 #1
avatar+1280 
+1
Best Answer

To complete this problem, we must make an important observation.

 

NOTE: 

\(3 + 4 + 5 = 3 *4 \\ 13 + 14 + 15 = 3 * 14\)

 

Now, we just have to figure out \(3 [ 4 + 14 + 24 + ....... + 994 ] = \)

 

There are 100 terms in the sequence, so we have

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

 

Thanks! :)

NotThatSmart May 28, 2024

3 Online Users

avatar
avatar