19/10/2020
*WISDOMLINK MATHEMATICAL TRICKS*
*(1)* Suppose we need to find the square root of large numbers such as 4489 without the use of calculator
Step 1: The unit digit in this number is 9, which can be a unit digit of its square root number such as 3 or 7. Because 32 is 9 and 72 is 49.
Step 2: Now let us consider the first two digits that is 44 which comes between the squares of 6 and 7 because 62 < 44< 72
Step 3: We can assume that the ten’s digit of the square root of 4489 is the lowest among the two numbers i.e. 6 and we need to find the unit digit of the square root of the number 4489.
Step 4: Now, we need to find between 63 or 67 which is the square root of 4489.
Step 5: Since the ten’s digit is 6 and the next number is 7, we need to multiply both the numbers like 6 x 7 = 42 and since 42 is less than 44.
Step 6: Square root of 4489 will be the bigger number between 63 and 67 i.e. 67.
Therefore, √4489 = 67
*(2)* When counting a percentage value (e.g 40% of 300). Divide both side by 10 and multiply the result
(4 x 30)= 120
*(3)* To multiply 9 by 5, fold down the fifth finger from the left. Count fingers on either side of the "fold" to get the answer. In this case, the answer is 45.
To multiply 9 times 6, fold down the sixth finger, giving an answer of 54.
*(4)* The 11 Rule
This is a quick way to multiply two-digit numbers by 11 in your head.
Separate the two digits in your mind.
Add the two digits together.
Place the number from Step 2 between the two digits. If the number from Step 2 is greater than 9, put the one's digit in the space and carry the ten's digit.
Examples: 72 x 11 = 792.
57 x 11 = 5 _ 7, but 5 + 7 = 12, so put 2 in the space and add the 1 to the 5 to get 627.
*(5)* If you multiply 6 by an even number, the answer will end with the same digit. The number in the ten's place will be half of the number in the one's place.
Example: 6 x 4 = 24.