Friday, September 18, 2015

Short cut cubing of any three digit number just in few seconds with help of Horner`s method for polynomial evaluation


We can utilize following algebraic expansion of Horner`s method for polynomial evaluation to easily find cube of any three digit number
(z + d) 3 = z x [z x (z + 3d) + 3d2] + d3
Where, d will always be one of the numbers between (+/-) 1 to (+/-) 50.
For example,
To find cube of the number 323,
Let, z = 300 and d = 23
So,
(z + d) 3 = z x [z x (z + 3d) + 3d2] + d3
(300 + (23)) 3 = 300 x [300 x (300 + 3(23)) + 3(23)2] + (23)3
(323)3 = 300 x [300 x (300 + 69) + 3(23)2] + (23)3
= 300 x [300 x 369 + 3(23)2] + (23)3
= 300 x [300 x 369 + 1587] + (23)3
= 300 x [110700 + 1587] + (23)3
= 300 x 112287 + (23)3
= 33686100 + 12167
= 33698267

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