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Wednesday, September 4, 2013

Multiplication tips and tricks in Maths

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To pace your calculation in the competitive examinations you need to sharpen your multiplication skills. You must multiply fast with accuracy. In competitive examinations like CAT, MAT, Civil Services, CAD, SSC, IBPS-PO etc. calculation need to be more accurate and fast. Time is major factor in Banks examinations where calculation can let you cross the rope first. Today so we are going to talk about the some techniques to do fast multiplication with larger number. The multiplication  tips and tricks in Maths for fast multiplication. 

Basic Multiplication tips and tricks in Maths

  • Rule 1  :  Square of no. with 1 as digits 
To calculate the square with only 1 in it we need to count the number of 1's in it and then write in forward up to that number and reverse back, that is the solution.

Syntax : 1111.....n times square is 123...n(n-1)(n-2)....321

Examples : 
  1. 112 =  121 (n=2 so 1...n...1, i.e. 121) 
  2. 11112 =  1234321 (n=4 so write 1234 and then backward 321 hence 1234321

  • Rule 2  :  Square of no. end with 5
To calculate the square of number ending with 5, remove 5 from the number and multiply the number formed with it immediate successor. Put 25 in right of the product got.

Syntax : (n)5, the square is ((n)*(n+1))25

Examples :  
  1. 252 = 625 (n=2, n+1=3, n*(n+1)=6 so ans is 625)
  2. 652 = 4225 (n=6, n+1=7, n*(n+1)=42 so ans is 4225)
  3. 10452  = 1092025 ( n=104, n+1=105, n*(n+1)=10920 so ans is 1092025)
  • Rule 3  :  Square of no. with 6 as only digits
To calculate the square of number with 6 as only digits, we have to do like we did for 1 in Rule 1.  One way is to use Rule 1 and multiply no. with 36 but it may be hard if digits grows. Rule is that for only 1 digit that 6 remember it 36 the square. Now we follows the rule from 2 digits onward. Count no of 6, then write that one times less 4 then 3 same one times less of count  5 and add last digit as 6.

Syntax : (6......6)n time, the square is (4....n times)3(5 .... n times)6

Examples :  
  1. 662 = 4356 (n=2, so  4 n-1i.e 1 times then 3 then one time 5 append by 6 i.e. 4356)
  2. 66662 = 44435556 (n=4 n-1=3 so trend is 44435556 ans.

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