how to find cube and cube root of a number

Topic:1 How to find the cube root of a number

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Before we are going to the topic of cube root of number faster we need to learn a simple table for easy shortcuts

Number             Cube         Last digit

     —————————————————-
     1                             1                          1
     2                             8                          8
     3                           27                          7
     4                           64                          4
     5                         125                          5
     6                         216                          6
     7                         343                          3
     8                         512                          2
     9                         729                          9
   10                        1000                         0         
The simple trick to remember the last digit of this table because this table is very important to find the cube root

For  numbers     1,4,5,6,9,0 is same the last digit occurs 
              Number 2 flips 8 and vice versa
              Number 3 flips 7 and vice versa

Now we will learn the basic procedure to solve the cube root of a number

  1. Take the unit digit same to the result.
  2. Leave the last three digits of the number.
  3. The last step is to find the nearest cube and put the left side of the unit digit.
  4. Now you will get the result of the cube root.
Now we will solve the examples of the cube root

1.find the cube root of 39,304?
Ans)  From the above procedure

  1. first finding the unit digit so it is 4
  2. Leaving the last three numbers   so  leave304 we get remaining 39
  3. find the nearest cube for 39 which is 27=  3
  4. Finally, club the answer to get the cube root of 39,304
          which is the cube root of 39,304= 34

1.find the cube root of 636,056?

Ans)  From the above procedure

  1. first finding the unit digit so it is 6
  2. Leaving the last three numbers   so  leave 056 we get remaining 39
  3. find the nearest cube for 39 which is 512=  8
  4. Finally, club the answer to get the cube root of  636,056
          which is the cube root of 636,056= 34

Topic2: How to cube a number in just 5sec

Now we are learning about cube of a two digit number

Now   we divide into Four categories which is below

  • Numberr starts with 1
  • Number Ends with 1
  •  Same Number
  • Different Numbers

Similer topic : How to square a five digit number  

1. Number starts With “1”.

The procedure is just 1, x1,x2,x3  Here X is the Second digit of a Number

and in a second line leave the first and last digits and then double the remaining numbers and Add the now then we get result


For Example  123=       1       2       4        8
                                       +          4       8         
                                       —————————–
                                            1      7      2        8

                         Now  123=  1728       
                                               
2.Number Ends With “1”

The procedure is reverse of above 
  x3,x2,x1,1 like this  here x is the first value
and in a second line leave the first and last digits and then double the remaining numbers and Add the now then we get result

For Example     313  =        27        9         3          1
                                        +                18         6     
                                          ———————————-
                                                29        7          9         1
                               
                           Ans  313= 29791    
                             
3.Same number repeated:
The Procedure for this  forall four we just enter as x3,x3,x3,x3 same here X is same so no issue andin a second line leave the first and last digits and then double the remaining numbers and Add the now then we get result

For Example    223 =         8        8        8       8 
                                            +         16      16    
                                            —————————
                                              10      6        4        8
                            Ans   223 = 10648

4.Different number comes:
Here is different from all
Here we consider 1st digit as X and 2nd Digit as Y
The procedure    x3,(x2*y),(y2*x), y3
and a second line leave the first and last digits and then double the remaining numbers and Add the now then we get result


For Example   233  =   8     12      18        27
                                      +        24      36
                                     —————————–
                                         12     1        6         7
                         Ans 223= 12167