## Maths Tricks

In this post, we’ve tried to summarise some awesome *maths tricks *and* maths shortcuts* that will speed up your calculations. Remember to share with your friends.

## How to divide a large number by 5 within few seconds?

Step 1: Multiply the number by 2. Step 2: Move the decimal point in the product one place to the left.

EXAMPLE: 195 / 5, Step 1: 195 x 2 = 390.0 Step 2: Move the decimal one place to the left: 39.0 Try 392978 / 5!

## Multiplication of a Three digit numbers

175 x 157 = ? The result of multiplication of three digit number is 175 x 157 = 27475. Step 1: Multiply (5 x 7) = 35 (note down 5 carry 3) Step 2:Then do cross multiplication (7 x 7 + 5 x 5 + 3 (add carry)) = 77 (note down 7 carry 7). Step 3: Again (1 x 7 + 1 x 5 + 7 x 5 + 7 (add carry)) = 54 (note down 4 carry 5). Step 4:do cross multiplication and add carry (1 x 5 + 1 x 7 + 5 (add carry)) = 17 (note down 7 carry 1). Step 5: Again (1 x 1 + 1) = 2, note it down. And finally the result we get 27475

## EXCEPTIONAL DIVISION RULE FOR 4

If a number is divisible by four the last two digit are divisible by 4 (or are zeros). EXAMPLE. 45624 last two digit is 24 24 is divisible by 4 then 45624 is divisible by 4.

## GOLDEN DIVISION RULE FOR 3

If a number is divisible by three, the sum of its digits will be divisible by 3. EXAMPLE 372 = 3 + 7 + 2 = 12 A corollary of this is that, any number made by rearranging the digits of a number divisible by 3 will also be divisible by 3.

## Squaring Technique to speed up calculations

In case of two digit number deduct last digit and add it to another number and then add square of same. Example: (53*53)=? = (53+3) * (53-3) + (3*3) =(56*50) + 9 = (560*5) + 9 = 2800 + 9 = 2809

## Multiplication of a Three digit numbers – 175 x 157 = ?

The result of multiplication of three digit number is 175 x 157 = 27475. Step 1: Multiply (5 x 7) = 35 (note down 5 carry 3). Step 2:Then do cross multiplication (7 x 7 + 5 x 5 + 3 (add carry)) = 77 (note down 7 carry 7). Step 3: Again (1 x 7 + 1 x 5 + 7 x 5 + 7 (add carry)) = 54 (note down 4 carry 5). Step 4:do cross multiplication and add carry (1 x 5 + 1 x 7 + 5 (add carry)) = 17 (note down 7 carry 1). Step 5: Again (1 x 1 + 1) = 2, note it down. And finally the result we get 27475

## Multiplication of Three and Two digit numbers 295 x 19 = ?

The result of multiplication of three and two digit number is 295 x 19 = 5605. Step 1: Multiply 5 x 9 = 45 (note down 5 and carry 4). Step 2:Then do cross multiplication and add carry (9 x 9 + 5 x 1 + 4) = 90 (note down 0 and carry 9). Step 3: Again do cross multiplication and add carry (2 x 9 + 1 x 9 +9) = 36 (note down 6 and carry 3). Step 4: Now multiply of left numbers and add carry (2 x 1 + 3) =5, note it down. And finally the result we get 5605

## Multiplication of Two digit numbers Shortcut tricks: 13 x 13 =?

The result of multiplication of two digit number is 13X13 = 169. Step 1: Multiply 3X3 =9 Step 2: Do Cross-multiplication (1X3) = 3 and (1X3) = 3 Step 3: Add both the result (1X3 + 1X3) = 6 and write down to the left of 9 (result of step 1). Step 4: Multiply left hand side numbers (1X1) = 1 and write down to the left of 6 (result of step 3). Finally the result we get 169. (Try to calculate all four steps in mind)

## Square root of a perfect square

Example: √5184 Step 1: Pair the numbers from right to left 5184. We get two pairs. Therefore, the answer is a 2 digit number. Step 2: Find a number whose square is the nearest to second pair 51. Square of 7 = 49 and square of 8 = 64. 49 is less than 51 . Therefore first digit of square root is 7. Step 3: Look at last digit which is 4 of the number 5184 . As square of 2 = 4 and square of 8 = 64 both end with 4 , the answer could be 72 or 78 . Step 4: As we know square of 75 = 5625 greater than 5184 , √5184is below 75 . So, √5184 =72

## Multiply Up to 20X20 In Your Head

In just FIVE minutes you should learn to quickly multiply up to 20×20 in your head. With this trick, you will be able to multiply any two numbers from 11 to 19 in your head quickly, without the use of a calculator. Try this: Take 15 x 13 for an example. Always place the larger number of the two on top in your mind. Then draw the shape of Africa mentally so it covers the 15 and the 3 from the 13 below. Those covered numbers are all you need. First add 15 + 3 = 18 Add a zero behind it (multiply by 10) to get 180. Multiply the covered lower 3 x the single digit above it the “5” (3×5= 15) Add 180 + 15 = 195.

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