Cube

Fast trick to find the cube

Find cube of '18'.

STEP 1 :

Formula for cube -

(a + b)3 = a3 + 3a2b + 3ab2 + b3

or

a3 + a2b + ab2 + b3
2a2b + 2ab2

= a3 + 3a2b + 3ab2 + b3

1 + 8 + 64 + 512
16 + 128

1 + 24 + 192 + 512

= 1000 + 2400 + 1920 + 512

= 5832

so cube is 5832