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!

Step 1: Consider the original number and imagine a space between two digits.
Step 2: Then, add the two digits and put the sum in the space.

EXAMPLE: 52 x 11,
Step 1: Write 52 as 5_2.
Step 2: Then, 5(5+2)2=572.
Try 49 x 11!

Step 1: Multiply the successor of ten's digit of the number with ten's digit.
Step 2: Square 5 to get 25.

EXAMPLE: Square of 25
Step 1: Multiply ten's digit 2 with its successor 3, 2 x 3 = 6
Step 2: Square of 5 = 25
So, square of 25 = 625
Try square of 55!

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

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

In just FIVE minutes you should learn to quickly multiply up to 20x20 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" (3x5= 15) Add 180 + 15 = 195.

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.

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.

Add first number and last digit of the second number take zero in the third place of this number then add product of last digit of the two numbers in it. Let me explain this rule by taking examples 13*19 = ? = (13+9)*10 + (3*9) = 220 + 27 = 247

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

Step 1: First we know that 98^2 is double of 98 that is = 98 x 98 =? At first we count the number of less from 100. That is the above 98 is 2 less from 100. Step 2: Now we are going to multiply 2 x 2 = 4 and note down this 4 (that are come from both less 98 x 98 from 100). Step 3: Put one Zero left from 4 and now subtract the less number is 2 from 98 that is (98 - 2) = 96 and the answer is 9604.

76^2 Step 1: put down 6 Step 2: Multiply 2 with (7 + 1) = 16 and add 16 +1 = 17.put down 7 and carry 1. Step 3: Multiply 7 with (7 + 1) = 56 + carry 1 = 57 put down 57 Answer is 5776

Square and Square Root of 114^2 Answer: we separate the 114 like this (11/4)^2 Then applied previous formula on it =11^2 / 2 x 11 x 4 / 4^2 =121 / 2 x 11 x 4 / 16 =12996 We apply the formula a^2+ 2.a.b + b^2 Step 1: note down 6 carry 1 Step 2: add carry 1 to 88 = 89, note down 9 carry 8. Step 3: add carry 8 to 121 and note down 129 = 12996 Note: we can also separate 114 to find square like (1/14) ^2

Here's what you can try - Square and Square Root of two digit get using Formula - Formula: (a+b)^2 = a^2+2ab+b^2 i.e., (a / b)^2= a^2/ 2ab / b^2 We applied this formula to obtain the square of a number Example : ( 57 )^2 = ( 5 / 7 )^2 Answer: Apply formula of a^2+2ab+b^2 Consider, A as 5 and B as 7 =5^2/ 2 X 5 X 7 / 7^2 =25 / 2 X 5 X 7 / 49 A^2=25, b^2=49 2ab = 2 X 5 X 7 = 70 =25 / 70 / 49 Step 1: Put down 9 carry 4 Step 2: add carry 4 to 70 = 74 put down 4 carry 7 Step 3: add carry 7 to 25 = 32 put down 32 and answer is 3249, = 3249

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

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

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)

The result of the addition is 5+55+555 = 615. Shortcut Tricks - Step 1: Take 5 Common and Replace all 5 with 1. 5(1+11+111). Step 2: Count number of digits in each number, i.e., 1=1(digit), 11=2(digit), 111=3(digit) and write down all digits together that is 123. Step 3: Multiply 5X123=615. The final result is 615.

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