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Math tricks

Brainteasers that appear difficult at first glance. Discover the trick that makes them easy!

These questions usually become easy by uncovering a simple trick. Reading the question carefully may help uncover clues that lead to a solution.

Example 1

Add a single line to the equation in order to make it true.

105 + 2 + 5 = 350

Solution: Add a line to the second plus sign in order to make it into a four.

Example 2

Is it possible to make the following equation true without changing it at all?

8 + 8 = 91

Solution: Turn it or look at it upside down!

16 = 8 + 8

1. Find the product of the following series:

(x-a) (x-b) (x-c) ..... (x-z)

Zero. All factors are multiplied by the factor (x-x) which is zero.

2.Change two letters, and add 3 numbers in order to make a common everyday sequence.


Place the number '1' at the beginning of the word.

Replace the two 'A's with '2' and '3':

1ST, 2ND, 3RD

3. In what way is it possible to fence off the largest area with a 2x2 meter fence?

Fix the fence in a circle around you and declare yourself to be on the outside.

4. Fill in the blanks with two words that create a logical sequence that is not 'first,' 'second', 'third,' .... 'eighth.'

__, __, third, fourth, fifth, sixth, seventh, eighth

Whole, half, third, ...

5. A spy is surveilling the entrance to an important building.

When someone entered, the doorman said twelve, and the reply was six. On the second entry, the doorman said six, and the reply was three. Being in a hurry, the spy approached the door with no further data points. The doorman uttered ten, and the spy replied five and was turned away.

Which number would have granted him access?

The spy should have answered three, the amount of letters in 'ten'.

6. When multiplied against itself, what number will result in the following number that includes the numbers (1 - 9) in increasing order and then decreasing in order from 9?


(111,111,111 * 111,111,111) = 12,345,678,987,654,321

View the pattern

11 * 11 = 121 (3 digits)

111 * 111 = 12321 (5 digits)

1111 * 1111 = 1, 234, 321(7 digits)


111, 111, 111 * 111, 111, 111 = 12345678987654321(17 digits)