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Question

What will come in place of the question mark (?) in the following equation if '+' and '×' are interchanged and '-' and '÷'are interchanged?

2 + 6 ÷ 8 - 4 × 14 = ?

The correct answer is

24

Solving Equations with Symbol Interchange

This problem requires us to evaluate a mathematical expression after interchanging certain operators according to given rules. We are given an equation and rules for swapping the '+' with '×' and '-' with '÷'. Let's break down the steps to solve this.

Understanding the Symbol Interchange Rules

The problem states the following interchange rules:

  • The '+' symbol is interchanged with the '×' symbol. This means wherever we see '+', we should use '×', and wherever we see '×', we should use '+'.
  • The '-' symbol is interchanged with the '÷' symbol. This means wherever we see '-', we should use '÷', and wherever we see '÷', we should use '-'.

We can represent these interchanges in a simple table:

Original Symbol New Symbol
$+$ ×
× $+$
$-$ ÷
÷ $-$

Applying the Interchange to the Equation

The original equation given is:

$$2 + 6 \div 8 - 4 \times 14 = ?$$

Now, let's apply the symbol interchange rules to this equation:

  • The '+' between 2 and 6 becomes '×'.
  • The '÷' between 6 and 8 becomes '-'.
  • The '-' between 8 and 4 becomes '÷'.
  • The '×' between 4 and 14 becomes '+'.

So, the new equation after the symbol interchange is:

$$2 \times 6 - 8 \div 4 + 14 = ?$$

Solving the Transformed Equation

Now we need to solve the new equation: $2 \times 6 - 8 \div 4 + 14$. We must follow the order of operations (BODMAS/PEMDAS) which dictates the sequence of calculations: Brackets, Orders (powers and square roots), Division and Multiplication (from left to right), Addition and Subtraction (from left to right).

Let's solve step-by-step:

  1. Division: Perform the division first. $8 \div 4 = 2$. The equation becomes: $$2 \times 6 - 2 + 14$$
  2. Multiplication: Next, perform the multiplication. $2 \times 6 = 12$. The equation becomes: $$12 - 2 + 14$$
  3. Subtraction and Addition: Finally, perform the subtraction and addition from left to right. $$12 - 2 = 10$$ $$10 + 14 = 24$$

So, the value of the expression after the symbol interchange is 24.

Final Result

After interchanging the operators and solving the new equation according to the order of operations, we find that the value of the expression is 24.

Revision Table - Symbol Interchange

Here's a quick look at how the operations changed:

Original Expression Segment Interchanged Segment
$2 + 6$ $2 \times 6$
$6 \div 8$ $6 - 8$
$8 - 4$ $8 \div 4$
$4 \times 14$ $4 + 14$

Putting it all together: $2 \times 6 - 8 \div 4 + 14$

Additional Information - Order of Operations (BODMAS/PEMDAS)

Understanding the order of operations is crucial for solving mathematical expressions correctly. The widely used mnemonics BODMAS and PEMDAS help remember the sequence:

  • BODMAS:
    • Brackets
    • Orders (Powers, Roots)
    • Division and Multiplication (from left to right)
    • Addition and Subtraction (from left to right)
  • PEMDAS:
    • Parentheses
    • Exponents (Powers, Roots)
    • Multiplication and Division (from left to right)
    • Addition and Subtraction (from left to right)

In our problem, we first performed division ($8 \div 4$), then multiplication ($2 \times 6$), and finally subtraction and addition from left to right ($12 - 2 + 14$).

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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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