Numbers - General Aptitude

Q1:

3897 x 999 = ?

A 3883203

B 3893103

C 3639403

D 3791203

E None of these

ANS:B - 3893103

3897 x 999 = 3897 x (1000 - 1)
  = 3897 x 1000 - 3897 x 1
  = 3897000 - 3897
  = 3893103.