[OK] Privacy Policy  -  Terms & Conditions  -  See DetailsWe use cookies to personalise content and ads. We also share information about your use of our site with our advertising partners who may combine it with other information you've provided to them or they've collected from your use of their services.

Puzzle Details

What is the sum of...

...all of the numbers from 1 to 1000?

[Ref: ZONR]

It's easiest to see that the first and last number are 1 and 1000, which add to 1001.

The next two numbers we can add are 2 and 999, which add to 1001.

The next two numbers to add are 3 and 998, which add to 1001.

We can keep doing this 500 times, and in each case they add to 1001.

And 500 x 1001 = 500,500.

Our Favourite Illusions

 Shadow Illusion Are the squares A and B the same colour? Spinning Dancer Which way is the dancer spinning? Impossible Waterfall? Is the water flowing uphill in this impossible waterfall? The Butterfly A colourful butterfly?
 Duck Or Rabbit? Is this a duck or a rabbit? Hidden Faces Can you find his three daughters as well? Blind Spot An amazing demonstration of your blind spot. Impossible Prongs? Impossible prongs?
 What Am I? Can you tell what this is a picture of? Who Turned To? Who is missing? Same Eyes? Are her eyes the same colour? Parallel Cafe Wall Lines? Are the horizontal lines parallel?