For example, Suppose the triangle (∆) means addition.
Math Trick
We know that triangle is a plane figure but here it has been assigned the value of addition (+).
Thus, 3 ∆ 5 ⇒ 3 + 5 = 8
In this way, two work out such questions substitute the assigned/ implied meanings of the symbol or sign and proceed accordingly.
To solve this type of questions, substitute the real signs in the given expression and then solve the expression according to the BODMAS rule.
Order of Operations – BODMAS
Example: If + means ÷, × means –, ÷ means × and – means +, then, 8 + 6 × 4 ÷ 3 – 4 = ?
(a) – 12
(b) – 20/3
(c) 12
(d) 20/3
Ans: (c)
Using the given symbols, we have:
Given expression: = 8 ÷ 6 – 4 × 3 + 4 = 4/3 – 4 × 3 + 4
= 4/3 – 12 + 4 = 20/3.
Example 1: If ‘÷’ means ‘+’, ‘–’ means ‘÷’, ‘×’ means ‘–’ and ‘+’ means ‘×’ then, 62 ÷ 8 – 4 × 12 + 4 = ?
(a) 16
(b) 26
(c) 1/16
(d) 6
Ans: (a)
Given expression, 62 ÷ 8 – 4 × 12 + 4 = ?
According to question, after replacement of mathematical sign
62 + 8 ÷ 4 – 12 × 4 = ?
= 64 – 48 = 16
Hence, ? ⇒ 16
Example 2: If ‘–’ means ‘+’, ‘+’ means ‘–’, ‘×’ means ‘÷’ and ‘÷’ means ‘×’; then which of the given equations is correct?
(a) 30 + 5 – 4 ÷ 10 × 5 = 58
(b) 30 + 5 ÷ 4 – 10 × 5 = 22
(c) 30 – 5 + 4 ÷ 10 × 5 = 62
(d) 30 × 5 – 4 ÷ 10 + 5 = 41
Ans: (d)
From option 4:
30 × 5 – 4 ÷ 10 + 5 = 41
According to question, after replacement of mathematical sign
30 ÷ 5 + 4 × 10 – 5 = 41 = 6 + 40 – 5 = 41 = 46 – 5 = 41
Hence option (4) is correct.
177 videos126 docs197 tests

1. What are some tricks for performing mathematical operations quickly and accurately? 
2. Can you provide an example of using the distributive property for multiplication? 
3. How can mental math techniques like rounding and estimation help in mathematical operations? 
4. Are there any shortcuts for addition and subtraction that can save time? 
5. How can breaking down complex operations into simpler ones help in mathematical calculations? 
177 videos126 docs197 tests


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