Syvum Home Page

Home > Math Puzzles & Brain Teasers > Print Preview

Math Puzzles & Brain Teasers


Add Quickly

View Puzzle Solve Puzzle

Hide all answers   View all answers   Print   Try the Quiz

Can you find a quick and elegant way to add the numbers from 1 to 42 ?

In other words, what is the sum you obtain in the following case:

1 + 2 + 3 + ....... + 42 =
Answer: 903

Solution:

Here's an elegant way:

1 + 42 = 43
2 + 41 = 43
3 + 40 = 43
.....................
.....................
21 + 22 = 43

Adding the above equations gives

1 + 2 + 3 + ....... + 42 = 21 × 43 = 903

Food for thought:

The general formula is:

1 + 2 + 3 + ....... + n = n (n + 1) / 2.

Is the formula valid when n is an odd integer?


  Try the Quiz :     Puzzles & Brain Teasers : Add Quickly

puzzle : image for addition

Contact Info © 1999-2017 Syvum Technologies Inc. Privacy Policy Disclaimer and Copyright
Previous
-
Next
-