Difficulty: Easy
Correct Answer: 25
Explanation:
Introduction / Context:
This question tests the fundamental concept of the order of operations in arithmetic, often known by the acronyms BODMAS or PEMDAS. Correct calculation requires that multiplication and division are carried out before addition and subtraction. Misunderstanding this rule leads to different and incorrect results in simple looking expressions.
Given Data / Assumptions:
Concept / Approach:
The correct approach is to remember that multiplication has higher precedence than addition. This means we first compute the product 2 × 10 and then add the result to 5. We must not simply go from left to right without considering precedence, because that would ignore the basic rules of arithmetic that every aptitude test expects you to follow.
Step-by-Step Solution:
Start with the expression: 5 + 2 × 10.According to BODMAS or PEMDAS, handle multiplication before addition.Compute the product: 2 × 10 = 20.Now substitute this back: 5 + 20.Finally, add the numbers: 5 + 20 = 25.
Verification / Alternative check:
If someone incorrectly did addition first, they might try to add 5 + 2 to get 7 and then multiply by 10 to obtain 70. However, this would violate the standard order of operations. Rechecking the rules confirms that 2 × 10 must be carried out first. Therefore the consistent and verified answer is 25.
Why Other Options Are Wrong:
70 comes from wrongly doing (5 + 2) × 10. 20 and 30 result from partial or inconsistent calculations, such as forgetting to add 5 or adding incorrectly. 52 is formed by writing the digits 5 and 2 together instead of performing arithmetic. None of these follow the correct precedence rules for operations.
Common Pitfalls:
A very common mistake in such problems is ignoring BODMAS or PEMDAS and evaluating the expression strictly from left to right. In timed tests, candidates may rush and misread the expression. To avoid errors, always look for multiplication and division first, then handle addition and subtraction. Writing a small intermediate step helps reinforce the correct sequence.
Final Answer:
The correct value of the expression is 25.
Discussion & Comments