Some Fantastic Math Tricks

Here are Some of The Good Math Tricks , which may help us do the sums quickly …..
Hope This Helps You in the Future…..

Quick Multiplication
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.
That is It! Wasn't that easy? Practice it on paper first!

The 11 rule
To multiply any two digit number by 11:

For this example we will use 54.
Separate the two digits in you mind (5__4).
Notice the hole between them!
Add the 5 and the 4 together (5+4=9)
Put the resulting 9 in the hole 594. That's it! 11 x 54=594.

Square 2 Digit Number

Square a 2 Digit Number, for this example 37:
Look for the nearest 10 boundary
In this case up 3 from 37 to 40.
Since you went UP 3 to 40 go DOWN 3 from 37 to 34.
Now mentally multiply 34x40
The way I do it is 34x10=340;
Double it mentally to 680
Double it again mentally to 1360
This 1360 is the FIRST interim answer.
37 is "3" away from the 10 boundary 40.
Square this "3" distance from 10 boundary.
3x3=9 which is the SECOND interim answer.
Add the two interim answers to get the final answer.
Answer: 1360 + 9 = 1369

With practice this can easily be done in your head.

Quick Square
Step1: If you need to square a 2 digit number ending in 5, you can do so very easily with this trick.
Step2: Mulitply the first digit by itself + 1, and put 25 on the end.
Step3:That is all!
Step4: Ex:25 ie(2*(2+1))&25
Answer:625

Multiply by 5
Step1: Take any number, then divide it by 2
Step2:If the result is whole, add a 0 at the end.
Step3: If it is not, ignore the remainder and add a 5 at the end.
Step4: 2682 x 5 = (2682 / 2) & 5 or 0
Step5:2682 / 2 = 1341 (whole number so add 0)
Step6: Ans:13410
Step7: Letâ€™s try another:5887 x 5,2943.5 (fractional numbers (ignore remainder, add 5)
Answer: 29435

Tough Multiplication
Step1: If you have a large number to multiply and one of the numbers is even, you can easily subdivide to get to the answer
Step2:Ex:32 x 125, is the same as: 16 x 250 is the same as: 8 x 500 is the same as: 4 x 1000 = 4,000

Subtracting from 1,000
Step1:To subtract a large number from 1,000 you can use this basic rule: subtract all but the last number from 9, then subtract the last number from 10:
Step2:Ex:1000-648
Step3: subtract 6 from 9 = 3
Step4: subtract 4 from 9 = 5
step5: subtract 8 from 10 = 2
Answer: 352

Consecutive number trick

Step1: Pick any 5 consecutive numbers between ten and one hundred. Let's say your friend picks 51, 52, 53, 54, and 55.
Step2: Find the middle number, (call it the median). In your case, the median is 53.
Step3: Multiply it by ten (just add a zero to the median). eg. 53 X 10 = 530.
Step4: Divide (/) by 2. eg. 530 / 2 = 265.

page revision: 1, last edited: 10 Dec 2009 16:44
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