MATHS TRICK 5

MATH TRICK 5 says the short cut  of multiplication between 11 and 20  but one of the numbers is  a decimal.

Example 1 

11.5 x 12
(The short cut of 11 x 12 has been studied in Maths Trick 1)
Here the base number is  10
Step 1.   11.5 + 2    = 13.5  (OR 12 + 1.5 = 13.5      1.5 and 2 are unit digits)
Step 2    13.5 x 10   = 135 ( 10 is the base number)
Step 3     1.5 x 2      =     3    (This is also explained in Maths Trick 1)
Step 4      135 + 3    = 138
                                  == ===
Yes . That is the answer.

Example 2.

12.5 x 13
12.5  + 3   = 15.5
15.5 x 10  = 155
2.5 x 3      =  7.5
Add up : 155 + 7.5  = 162.5
Yes . That is the answer.

Example 3.

15.4  x  11
15.4 + 1 = 16.4 x 10 = 164 +1 x 5.4 = 169.4
                                                            =====

Example 4

17.2 x 12
Calculation should be in the head.
17.2 + 2 =19.2         192 + 2 x 7.2 = 206.4

Exercise

1.      16.5 x 11

2.      19. 5 x 13

3.      18 x 13.5

4.      14 x 14.4

5.      15 x12.5

MATHS TRICK 4

 Maths Trick 1 says how to multiply up to 20 x 20 in our head.
Here we can play more .
MATHS TRICK 4 says how to multiply up to 30 x 30

Example 1.         21 x 22 

(Here we take 20 as the base number as 10 in  Maths  Trick 1)

Base number - 20
21  =  20  + 1
22  =  20  + 2

Step 1 :  21      +1
              22      +2
( +1 is the difference between 21 and 20 and  +2 is the difference between 22 and 20)

Step 2  :   21 + 2    =  23   OR  22 + 1 = 23  (CROSS SUM)

Step 3. :   23 x 20   = 460  (20 is the base number)

Step 4  :   1  x  2     =    2  

Step 5  : (Add 460 and 2)    460 +2  = 462  

Yes . That is the answer.

We can forget all these steps after getting it .

Example 2. 
                      23  x  24

Step 1 :     23  +  4   =  27
Step 2 :     27 x 20   =  540  ( short cut:  27 x 2 = 54, 27 x 20 = 540)
Step 3 :     3 x 4       =    12
Step 4 :    540 +12   = 552
                                   ===
Example 3
                    28 x 29

28 + 9   =    37
37 x 20 =    740       (37x2 =74 , 37 x 20 = 740)
8 x 9     =      72
740  +  72 =  812

Yes. That is the answer.

Example 4.
                   26 x 29

The multiplication must only be in your head

26 + 9 = 35 x 20 = 700 + 54 = 754
                                                 ===
Exercise

1.      22 x 25

2.      23 x 27

3.      24 x 29

4.      28 x 21

5.      25 x 29 

MATHS TRICK 3

An easy way to square any number  ending with 5
The way of squaring can be done like this:

Example  1 
                       15 ²  = 15 x 15  =225
        short cut : 
Step 1.  Separate the 5 from the  number to be squared        1    5   
Step 2. The remaining portion of the number is multiplied by the immediate higher number  1 x 2 =2
Step 3.  Suffix 25 to the result of   Step 2       =       225
 

Example 2.

                           25 ²            =  2     5
                                    2 x 3 =  6   25
                                             =  625

Example 3.                 35 ²   = 3 x 4 = 12 25
                                             = 1225
Example 4.                 85 ²   = 8 x9 = 72  25
                                             = 7225
Example 5          115 ²    = 11 x 12   ( Here we apply the Maths Trick 1)
                          11 + 2 = 13 0  +
                            1 x 2  =      2
                                         ------                            
                                          132

                         115 ² = 13225
                                                                        Maths can be fun ! 


 Example 6.      225 ²       = 22 x 23 (Short cut for this multiplication will be later)
                                         = 506
                         225 ²        = 506 25
                                         = 50625
                                            ====
         



                    

MATHS TRICK 1 , MATHS TRICK 2

MATHS TRICK 1 

Multiplication Table : 11 to 19

It is difficult to study multiplication table up to 9 for some students. An important study reveals that more than 50 per cent of the student body ,  is away from mathematics.

Here is your opportunity to acquire   multiplication table from 11 to 19.

Study carefully and be a master of multiplication tables in seconds and Master of  Maths later.

Example I .  11 x 12

Step 1 :  11  + 2  = 13
      OR  12  + 1  = 13

( The first number is added to the unit digit of second number  (11+2)  OR  Second number is added to the unit digit of first number  (12+1) )

Both give the same result

Step 2 :  The result is multiplied by 10
                          13 x 10   = 130

Step 3 :  Product of the unit digits of the given numbers.
                              1  x 2  =  2    (1 of 11 and 2 of 12)

Step  4 : Add the results of  Step 2 and Step 3

                           130+2 =   132                                        

                           11 x 12 = 132

Example 2
                16 x 17

             Step 1 :  16 + 7      =  23  (OR 17+6 =23)
             Step 2 :  23 x 10    =  230
             Step 3 :  6 x 7        =   42  (product of unit digits)
             Step 4 :  230+ 42  =  272   

                           16 x 17 = 272 
                                            
 Example 3.
                18 x 19
                            1 8 + 9  =    2 7 0
                                                     --
                              8  x  9  =      7  2
                                             --------
                                               3 4 2
                                              ====
                          18 x 19  = 342
 Example 4.
                1 3 x 1 9
                                 1 3 + 9  = 2 2 0
                                    9 x 3  =    2 7
                                                ---------
                                                 2 4 7
                                                =====
Brilliant, you solved the puzzle! 

No need of using pen and paper. You can multiply any number between 11 and  19 within 5 seconds.

MATHS TRICK 2

If one of the number is decimal

Example1 :  17.5 x 11

                 17.5 + 1   = 18.5
                 18.5 x 10  = 185
                  7.5 x 1    =     7.5
                 185+ 7.5 =  192.5

Example 2.  16 x 12.5
                    16 + 2.5  = 18.5   ----185  +
                      6 x 2.5  =                   15
                                                     -----
                                                      200
                                                      ===

Exercise 
1.    12 x 19
2.    13 x 13.5
3.    15 x 16.5
4.    19 x 14
 5.   17 x 14.5

MATHS TRICK 1

Multiplication Table : 11 to 19

It is difficult to study multiplication table up to 9 for some students. An important study reveals that more than 50 per cent of the student body , including matured is away from mathematics.

Here is your opportunity to acquire   multiplication table from 11 to 19.

Study carefully and be a master of multiplication tables in seconds and Master of  Maths later.

Example I .  11 x 12

Step 1 :  11  + 2  = 13
      OR  12  + 1  = 13 

( The first number is added to the unit digit of second number  (11+2)  OR  Second number is added to the unit digit of first number  (12+1) )

Both give the same result

Step 2 :  The result is multiplied by 10
                          13 x 10   = 130

Step 3 :  Product of the unit digits of the given numbers.
                              1  x 2  =  2    (1 of 11 and 2 of 12)

Step  4 : Add the results of  Step 2 and Step 3

                           130+2 =   132                                        

                           11 x 12 = 132

Example 2
                16 x 17

             Step 1 :  16 + 7      =  23  (OR 17+6 =23)
             Step 2 :  23 x 10    =  230
             Step 3 :  6 x 7        =   42  (product of unit digits)
             Step 4 :  230+ 42  =  272    

                           16 x 17 = 272 
                                            
 Example 3.
                18 x 19
                            1 8 + 9  =    2 7 0
                                                     --
                              8  x  9  =      7  2
                                             --------
                                               3 4 2
                                              ====
                          18 x 19  = 342
 Example 4.
                1 3 x 1 9 
                                 1 3 + 9  = 2 2 0
                                    9 x 3  =    2 7
                                                ---------
                                                 2 4 7
                                                =====
Brilliant, you solved the puzzle!  

No need of using pen and paper. You can multiply any number between 11 and  19 within 5 seconds.

A lot of  short cuts and tricks are waiting for you. Visit again.