Brain Teasers and Optical Illusions:

**7 Gallons of Water: (easy)**

You have a 3 gallon jug and a 5 gallon jug. You need to measure out exactly 7 gallons of water. How do you do it?

**The Missing Dollar: (medium)**

Three men in a cafe order a meal the total cost of which is $15. They each contribute $5. The waiter takes the money to the chef who recognizes the three as friends and asks the waiter to return $5 to the men.

The waiter is not only poor at mathematics

but dishonest and instead of going to the trouble of splitting the $5 between the three he simply gives them $1 each and pockets the remaining $2 for himself.

Now, each of the men effectively paid $4, the total paid is therefore $12. Add the $2 in the waiters pocket and this comes to $14.....where has the other $1 gone from the original $15?

**A number with an interesting property: (hard)**

When I divide it by 2, the remainder is 1.

When I divide it by 3, the remainder is 2.

When I divide it by 4, the remainder is 3.

When I divide it by 5, the remainder is 4.

When I divide it by 6, the remainder is 5.

When I divide it by 7, the remainder is 6.

When I divide it by 8, the remainder is 7.

When I divide it by 9, the remainder is 8.

When I divide it by 10, the remainder is 9.

It's not a small number, but it's not really big, either.

When I looked for a smaller number with this property I couldn't find one.

Can you find it?

**Wavy Lines Illusion:**

Are these lines straight and parallel or wavy?

**Look at the chart and say the color not the word:**

Your right brain tried to say the color, but your left brain was reading the word.

What do you see in this image?

Do you see a beautiful woman or a cool jazz horn blower?

**Bunny or Duck? **
Image Credit: J. Jastrow (1899)