Tips & Tricks in mathematics

Tips & Tricks in mathematics

• 2.
  Introduction In mathematics tricksare important to do calculation faster and easier. In these slides we will show you some tricks for fast and easy calculation.
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  Multiplying by 4 Thistrick is very simple and yet logical. To multiply any number by 4, just multiply it by 2 and then double the answer. The basic concept of this trick is that you can solve a multiplication problem by multiplying by its factors. Let’s assume the number is 25. Then: 25 x 4 25 x 2 = 50 50 x 2 = 100 25 x 4 = 100 This trick is based on a very simple fact: 2 x 2 = 4
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  Multiplication by 5 It'soften more convenient instead of multiplying by 5 to multiply first by 10 and then divide by 2. For example, 137×5 = 1370/2 = 685.
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  Multiplying by 12 12X 7 The first thing is to always multiply the 1 of the twelve by the number we are multiplying by, in this case 7. So 1 X 7 = 7. Multiply this 7 by 10 giving 70. (Why? We are working with BASES here.) Bases are the fundamentals to easy calculations for all multiplication tables. Now multiply the 7 by the 2 of twelve giving 14. Add this to 70 giving 84. Therefore 7 X 12 = 84
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  Multiplication of 2Numbers Step 1: Let us consider multiplying any two digit numbers, for example 23 x 24. Step 2: Choose the unit digit of both the numerals and deduct it from the given numerals. 23 - 3 = 20 24 - 4 = 20 Step 3: Now, select any one number (24) and add it with unit digit of another number(3) 24 + 3 = 27 Step 4: Then, multiply the result obtained in step 2 and step 3. 27 x 20 = 540 Step 5: Multiply the unit digit values. 4 x 3 = 12 Step 6: Finally, add values obtained from step 3 and step 4. 540 + 12 = 552 23 x 24 = 552
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  Multiplication of 3Numbers Step 1: Let us consider multiplication of three digit numbers 208 x 206. Step 2: Now, deduct the last digit from the respective numerals. 208 - 8 = 200 206 - 6 = 200 Step 3: Pick any one number and add it with the unit digit of another number. 208 + 6 = 214 Step 4: Now, multiply the result obtained in step 1 and step 2. 214 * 200 = 42800 Step 5: Then, multiply the unit digits of the given numbers. 8 * 6 = 48 Step 6: Add the values obtained in step 4 and step 5. 42800 + 48 = 42848 208 x 206 = 42848
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  To check divisibilityof a number 2- A number is divisible by 2 if it is even. 3- A number is divisible by 3 if the sum of the digits is a multiple of 3. Eg.)12-1+2=3 4-A number is divisible to 4 if the last two digits of the number are divisible by 4. 5-A number is divisible by 5 if the last digit is 5 or 0. 6-A number is divisible by 6 if the number is divisible by 2 and 3. 7-A number is divisible by 7 if you double the last digit and subtract it from the rest of the number and the answer is: 0, or divisible by 7. 8-The last three digits are divisible by 8. 9-The sum of the digits is divisible by 9. 10-The number ends in 0. 11-If you sum every second digit and then subtract all other digits and the answer is:0, or divisible by 11. 12-The number is divisible by both 3 and 4.
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  Squaring of numbersending with 5 65x65=4225 Multiply the previous number 6 to one more than itself 7. Then write 25.
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  Squaring two digitnumbers Say, you want a square of 13. Do this: add 3 (the last digit) to 13 (the number to be squared) to get 16 = 13 + 3. Square the last digit: 3² = 9. Append the result to the sum: 169.
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  Distributive Property The DistributiveProperty is an algebra property which is used to multiply a single term and two or more terms inside a set of parentheses. Eg.) 103+101=100(3+1)