To find the cube of numbers between 11 to 99

First learn the cubes of first 10 natural numbers

Lets Find the cube of 34

Step 1             Write the cube of 3 (tens place digit )

27

Step 2             Multiply the obtained cube by the ratio of unit place to tens place digit I;e 4/3 to get next
                       digits

(4/3)x27 = 36

                       Now you get next set of digits

27       36

Step 3           Multiply the obtained second set by the ratio of unit place to tens place digit again I;e 4/3 to    
                     get next digits

(4/3)x36 = 48

                    Now you get next set of digits

27       36        48

Step 4          Multiply the obtained third set by the ratio of unit place to tens place digit again I;e 4/3 to get
                    next digits

(4/3)x48 = 64

                   Now you get next set of digits

27      36      48      64

Step 5        Double the second set and third set digits as shown below and then add to get cube of number

                                                               12          15           6

                                                               27         36          48        64

                                                                   +      72           96

                                                             _______________________

                                                               39       123        150        64       ( Red digits are to be carry )

                                                              39       3        0       4

Thus Cube of 34 is 39304