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Simplification - Notes | Study Quantitative Techniques for CLAT - CLAT

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Simplification

VBODMAS Rule

  • When an expression involves the + and – signs, the order of operation is from left to right.
  • Thus 20 – 15 + 2 – 4 means that 15 is to be subtracted from 20 then 2 is to be added to the result and then 4 is to be subtracted from the result.
  • When an expression involves x and ÷ signs, the order of operation is from left to right. Thus 55 ÷ 5 x 3 means that 55 is to be divided by 5 and the result is to be multiplied by 3.
  • 45 x 5 ÷ 3 means that 45 is to be multiplied by 5/3.
  • When an expression involves all the signs (i.e. +, –, x, ÷) then division and multiplication must be performed before addition and subtraction.
Brackets
  • The expressions within brackets are to be treated as a single identity thus 6 x (3 – 2) means that 6 is to be multiplied by the difference of 3 and 2.
  • So 6 x (3 – 2) = 6 x 1 = 6

Note: Operations within the bracket are to be carried first.

Brackets are of 4 types. 

  • Bar bracket or Vinculum
  • Circular bracket ( )
  • Curly bracket { }
  • Square bracket [ ]

Removal of a bracket

  • 5 + (9 + 2) is equal to 5 + 11 = 16
  • 5 + (9 – 2) is equal to 5 + 7 = 12
  • The rule is that when a bracket is preceded by a + sign, the bracket may be removed without making any change in the expression.
  • Now consider the expressions when the bracket is preceded by a ‘–’ sign
  •  20 – (8 + 3) = 20 – 11 = 9 also 20 – (8 + 3) = 20 – 8 – 3 = 9
  • 20 – (8 – 3) = 20 – 5 = 15 also 20 – (8 – 3) = 20 – 8 + 3 = 12 + 3 = 15
  • The rule is that if a bracket is preceded by a negative (–) sign, the bracket can be removed by changing the sign of every term within the bracket.

Bracket within a bracket

  • Let us take an example
  • Supposing we want to simplify

Simplification - Notes | Study Quantitative Techniques for CLAT - CLAT

  • We will first remove the bar bracket then circular bracket, then curly bracket and at the last stage we remove the square bracket.
  • So the expression given above is

= 24 – [12 – {8 – (9 – 2 – 3)}]

= 24 – [12 – {8 – 4}]

= 24 – [12 – 4]

= 24 – 8

= 16

  • The rule of VBODMAS gives us the arrangement according to which an expression is to be simplified. VBODMAS stands for vinculum, brackets, of, division, multiplication, addition and subtraction respectively.
  • Algebraic Identities: The algebraic identities noted below are used as expression formulae:

 

General Rules For Solving Problems In Arithmetic

  • (a+b) (a-b) = a2 - b2 
  • (a+b)2 = a2 + b2 + 2ab 
  • (a – b) 2 = a2 + b2 – 2ab 
  • (a + b)3 = a3 + b3 + 3ab (a+b) 
  • (a – b)3 = a3 – b3 – 3ab (a–b)
  • a2 + b2  =  (a + b)2   – 2ab
  • a3 + b3 = (a+b) (a2 + b2 – ab) = (a+b)3 – 3ab (a+b) 
  • a3 - b3  =  (a – b) ( a2 + b2 + ab) =  (a–b)+ 3ab (a-b) 
  • a3 + b3 + c3 = (a + b + c) (a2 + b2 + c2 – ab – bc – ca) + 3abc If a + b + c = 0, then a3 + b3 + c3 = 3abc 
  • (a+b+c)2 = a2+b2+c2+2ab+2bc+2ca 
  • (a+b+c)3 = a3+b3+c3+3a2 (b+c) + 3b2(a+b)+3c2(a+b)+6abc [remember there are ten terms] 
  • To find the sum of a and b, given their difference and product:
    a + b = Simplification - Notes | Study Quantitative Techniques for CLAT - CLAT   
  • To find the difference of a and b, given their sum and product: a – b = Simplification - Notes | Study Quantitative Techniques for CLAT - CLAT

 Questions on Simplification 

  • Generally the types of questions which can be asked for simplification are of the following types.

 Type 1 

  • Questions involving expressions in which the items / numbers are either to be added or subtracted. The numbers may be integers or decimals.

 Type – II 

  • The numbers to be added or subtracted are fractions. The fractions may be pure or mixed fractions.

 Type – III 

  • The numbers or items in the expression are connected with the signs of multiplication or division e.g.

i) 1.6 x 20 x 12 + 30 x 2

ii) 2.21 ÷ 0.7 = ? + 5.5

iii) 4545 ÷ 50 ÷ 5 = ?

Type – IV 

  • These questions contain signs of multiplication, division, percentage, of, etc and also fraction e.g.

i) 35% of 495 + ? = 250

ii) Simplification - Notes | Study Quantitative Techniques for CLAT - CLAT

iii) 30% 150 + ? of 300 = 40 % of 450

 Type V

  • Square – roots and cube roots along with fractions etc. are there in this type of questions on simplification like.

Simplification - Notes | Study Quantitative Techniques for CLAT - CLAT

Type VI 

  • This type of questions may relate to surds and / or indices like

i) (19.7)5 ÷ (19.7)4 =?  

ii) 2310.5 x 235.1 ÷ 231.2 = 23?

Simplification - Notes | Study Quantitative Techniques for CLAT - CLAT

Type VII
  • Type VII may relate to inequalities or equalities with signs of (<, =, >)
The document Simplification - Notes | Study Quantitative Techniques for CLAT - CLAT is a part of the CLAT Course Quantitative Techniques for CLAT.
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