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Question

What will be the value of the following equation if ‘÷’ means ‘addition’, ‘+’ means ‘subtraction’, ‘-‘ means ‘multiplication’ and ‘×’ means ‘division’

54 × 6 – 7 ÷ 8 + 2 = ?

This question was previously asked in
SSC CGL 2018 (Tier 2) Statistics Previous Year Paper (22-feb-2018)
The correct answer is

69

Understanding the Symbol Substitution Problem

This question requires us to solve a mathematical expression where the usual meaning of arithmetic symbols is changed. We are given a set of rules for symbol substitution, and we need to apply these rules first before performing the calculations according to the standard order of operations.

Applying the New Rules to the Equation

The original equation is: \(54 \times 6 – 7 \div 8 + 2\)

The symbol substitution rules are:

  • ‘÷’ means ‘addition’ (\(+)\)
  • ‘+’ means ‘subtraction’ (\(-\))
  • ‘-‘ means ‘multiplication’ (\(\times\))
  • ‘×’ means ‘division’ (\(\div\))

Let's replace the symbols in the original equation based on these rules:

  • The symbol ‘×’ between 54 and 6 becomes ‘÷’ (division).
  • The symbol ‘–’ between 6 and 7 becomes ‘×’ (multiplication).
  • The symbol ‘÷’ between 7 and 8 becomes ‘+’ (addition).
  • The symbol ‘+’ between 8 and 2 becomes ‘–’ (subtraction).

So, the new equation after applying the symbol substitution is:

\(54 \div 6 \times 7 + 8 - 2\)

Solving the Mathematical Expression with Order of Operations

Now we need to solve the new equation \(54 \div 6 \times 7 + 8 - 2\). We follow the order of operations, often remembered by acronyms like BODMAS or PEMDAS.

  • B/P: Brackets/Parentheses (None in this equation)
  • O/E: Orders/Exponents (None in this equation)
  • DM: Division and Multiplication (from left to right)
  • AS: Addition and Subtraction (from left to right)

Let's solve step-by-step:

  1. Perform division: \(54 \div 6 = 9\). The equation becomes \(9 \times 7 + 8 - 2\).
  2. Perform multiplication: \(9 \times 7 = 63\). The equation becomes \(63 + 8 - 2\).
  3. Perform addition: \(63 + 8 = 71\). The equation becomes \(71 - 2\).
  4. Perform subtraction: \(71 - 2 = 69\).

The final value of the equation after symbol substitution and calculation is 69.

Final Answer Calculation Summary

Here is a summary of the steps:

Step Operation Equation
Original Substitute symbols \(54 \times 6 – 7 \div 8 + 2\)
1 Division (\(\times\) becomes \(\div\)) \(54 \div 6 \times 7 + 8 - 2\)
2 Division (from left) \(9 \times 7 + 8 - 2\)
3 Multiplication \(63 + 8 - 2\)
4 Addition (from left) \(71 - 2\)
5 Subtraction \(69\)

The value of the given equation after applying the symbol substitution rules is 69.

Revision Table: Symbol Substitution and Arithmetic

Original Symbol Means (New Operation)
‘÷’ ‘addition’ (\(+)\)
‘+’ ‘subtraction’ (\(-\))
‘-‘ ‘multiplication’ (\(\times\))
‘×’ ‘division’ (\(\div\))

Additional Information: Order of Operations

The order of operations is crucial in solving mathematical expressions correctly. It ensures that everyone gets the same result from the same expression. The widely used order is:

  • First, calculate anything inside Brackets or Parentheses.
  • Next, calculate Exponents or Orders (like square roots, powers).
  • Then, perform Division and Multiplication, working from left to right.
  • Finally, perform Addition and Subtraction, working from left to right.

Remembering this order helps avoid errors in calculations, especially when multiple operations are involved, such as in this symbol substitution problem.

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Similar Questions

  1. Which of the following interchange of numbers and mathematical signs would make the given equation correct?

    30 ÷ 6 × 4 + 15 - 35 = 25

  2. Select the correct combination of mathematical signs that can sequentially replace the * signs and make the equation correct.

    48 * 12 * 8 * 15 * 3 * 44

  3. By Interchanging the given two numbers which of the following equation will be not correct?

    9 and 6

  4. By Interchanging the given two numbers which of the following equation will be correct?

    2 and 8

  5. Which two signs should be interchanged to make the given equation correct?

    95 * 5 + 19 ÷ 2 − 21 = 36

  6. By interchanging the given two signs and numbers which of the following equation will be not correct?

    + and –, 3 and 5

  7. Select the correct combination of mathematical signs to sequentially replace the * signs and to balance the given equation.

    50 * 25 * 10 * 2 * 175

  8. Which two signs and two numbers should be interchanged in the following equation to make it correct?

    10 × 11 + 19 - 323 ÷ 3 = 50

  9. By interchanging the given two signs which of the following equation will be not correct?

    + and ÷

  10. By interchanging the given two signs and numbers which of the following equation will be not correct?

    × and +, 7 and 4

    I. 7 × 8 + 4 – 6 ÷ 3 = 57

    II. 4 × 8 – 9 ÷ 3 + 7 = 3


Important Questions from Logical Puzzle

  1. Seven persons P, Q, R, S, T, U and V like different watches namely W1, W2, W3, W4, W5, W6 and W7 (not necessarily in the same order). P and R do not like odd numbered watch. T likes W5. U does not like W2 or W3 or W6 or W7. P likes prime numbered watch. Q likes W4. S likes W2 or W7. Which of the following statement(s) is/are correct ?

    I. S likes W7.

    II. R likes W2.

    III. U likes W1.

    IV. V likes W3.

  2. If ‘+’ means ‘×’, ‘×’ means ‘÷’, ‘÷’ means ‘–’ and ‘–’ means ‘+’, then

    16 + 18 × 3 ÷ 6 = ?

  3. In a certain code language, ‘Today is last match’ is written as ‘Sa Te Mo Pt’, ‘Last king like your team’ is written as ‘De Ra Mo Lo Zs’, ‘Our team won today match’ is written as ‘Te Ra Pt Ae We’. What is the code for ‘Our won is Last’ in that code language?

  4. In a certain code language, ‘LETTER’ is written as ‘ZLZYIO’. What is the code for ‘ACTION’ in that code language?

  5. If A denotes ‘+’, B denotes ‘×’, C denotes ‘-’, and D denotes ‘÷’, then what will come in place of ‘?’ in the following equation?

    34 A 15 B 3 C 11 B 2 A (51 D 17) = ?

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