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Numbers - ( Arithmetic Aptitude)

Some Basic Formulae:
  1. (a+b)(a-b) = (a2-b2)
  2. (a+b)2= (a2+ b2+ 2ab)
  3. (a-b)2= (a2+ b2- 2ab)
  4. (a+b+c)2=a2+ b2+c2+ 2(ab+bc+ca)
  5. (a3+b3) = (a+b)(a2-ab+b2)
  6. (a3-b3) = (a-b)(a2+ab+b2)
  7. (a3+b3+c3- 3abc) = (a+b+c)(a2+b2+c2-ab-bc-ac)
  8. Whena+b+c= 0, thena3+b3+c3= 3abc.