Math Tricks

Math magic tricks can enliven any math session and instil a feeling of surprise and interest in students. Not only that, but math magic shifts the focus of algebraic thinking away from "What is the answer?" and towards "What is the trick?"

1. Percentage

Finding a percentage of a number might be difficult, but thinking about it in the correct words makes it a lot easier to grasp.

For example, to find out what 5% of 255 is, use the following formula:

Step 1: Shift the decimal point one position to the right. 255 becomes 25.5.

Step 2: Take 25.5 and divide it by 2. The result is 12.75. This solves 5% of 255 efficiently and easily.

2. Pi memorisation

Count the number of letters in each word of the line ‘How I wish I could calculate pi’ to learn the first seven digits of pi.

3.141592 is the result.

3. Close together method

(n + a)(n + b) = n (n + a + b) + ab

The formula applies to all numbers. However, it does not simplify effectively unless the numbers are comparable.

Here is how it works. The base number is n.

Consider an example: 54 * 56

= (50 + 4)(50 + 6)

= 50 ( 50 + 4 + 6) + (4 * 6)

= (50 * 60) + 24

= 3000 + 24

= 3024

Hence, 54 * 56 = 3024.

You may also round up to the nearest whole number. We add the product of two negative integers since the original values are less than the base. This method can also be applied to three-digit numbers.

4. Square a three-digit number that ends in 5 as quickly as possible.

As an example, consider the number 125. To find the square of this number, follow these steps:

Step 1: Consider 25 as the last two digits.

The number you get should go like this: _ _ _ 2 5

Step 2: Take the remaining digits (hundreds and tens place) as ‘n’. Multiply n(n+1).

Here, we take n=12. Hence, n(n+1) = 12(12+1) = 12*13 = 156.

Therefore, the number is 15625.

Hence, 125² = 15625.

5. Taking two-digit integers and multiplying them by 11

With this ingenious technique, multiplying two-digit integers by 11 is a snap. Add the two digits and place the total in the middle. For example, if you want to multiply 63 * 11, follow these steps:

Step 1: Add 6 and 3. So, 6 + 3 = 9.

Step 2: Insert 9 in between 6 and 3.

The answer is 693. Hence, 63 * 11 = 693.

6. Turning a repeating decimal into a fraction

There are three stages you must do to convert a repeating decimal into a fraction. First, identify the number that keeps recurring. For example, in the number 0.7387387348..., for example, 738 is the recurring number. Then calculate how many places that number has. In this example, the number 738 appears thrice. Finally, divide the repeated number by a number with the same number of places made up by nines, which in this case is 999. Reduce the proportion from 738/999 to 82/111, and you are done.

7. Addition of Larger Numbers

Addition is perhaps a fundamental mathematical process that can be completed with apparent ease. However, the process becomes increasingly difficult when dealing with larger numbers. Thanks to this quick Math hack, you can now add large numbers with absolute ease.

We explain this process by taking the help of complex numbers such as: 677 + 219

These numbers might seem to be overwhelming to add. However, if you round these digits off to the closest whole number and then initiate the process, then it can become easier to solve.

Consider 677 to be 680 by adding 3 and 219 to be 220 by adding 1.

Now add the results : 680 + 220

We would then obtain an initial answer “900”

Now, the final step involves subtracting the number that was added to the two variables from the initial answer of 900.

Therefore, 900 - (3 + 1) or 900 - 4

The Final Answer would be 896.

This is a very simple and straightforward technique that should be used by students regardless of their age and intelligence.

Final Overview

The tricks mentioned above will help students to save valuable time during examinations and will also allow them to gain more confidence to solve complex math equations more effectively.