Difficulty: Easy
Correct Answer: 31
Explanation:
Introduction / Context:
This question tests the correct use of the order of operations (often remembered as BODMAS or PEMDAS). The expression 3 × 3 × 3 + 3 + 3 ÷ 3 contains multiplication, addition, and division. To evaluate it correctly, we must perform multiplications and divisions from left to right before performing additions. Misordering the operations or grouping terms incorrectly can lead to wrong answers.
Given Data / Assumptions:
- The expression is 3 × 3 × 3 + 3 + 3 ÷ 3.
- Multiplication and division have the same precedence and are carried out from left to right.
- Addition is performed after multiplication and division.
Concept / Approach:
According to the order of operations, we first calculate all products and quotients in the order they appear from left to right, and then we calculate sums. There are no brackets or powers written explicitly here, so the only precedence issue is between ×, ÷, and +. Evaluating step by step avoids accidental grouping such as (3 × 3 × 3 + 3 + 3) ÷ 3, which would not follow the standard rules.
Step-by-Step Solution:
Step 1: Start with the expression: 3 × 3 × 3 + 3 + 3 ÷ 3.
Step 2: Evaluate the multiplications from left to right. First compute 3 × 3 = 9.
Step 3: Multiply that result by the next 3: 9 × 3 = 27. So the expression becomes 27 + 3 + 3 ÷ 3.
Step 4: Next handle the division 3 ÷ 3 = 1. After this step, the expression becomes 27 + 3 + 1.
Step 5: Now perform the additions from left to right: 27 + 3 = 30, then 30 + 1 = 31.
Step 6: Therefore, the value of the expression is 31.
Verification / Alternative check:
We can check by grouping the multiplication as 3^3 = 27 (since 3 × 3 × 3 is 3 cubed). Then the expression is 27 + 3 + 1 = 31, which matches the previously obtained result. Any rearrangement that changes the order of operations, such as dividing the entire sum by 3, leads to a different answer and is not allowed under standard rules.
Why Other Options Are Wrong:
Option 11 or 3.33 or 9: These results arise from misapplying the order of operations, such as incorrectly dividing the whole expression by 3 or performing addition before handling all multiplications and divisions.
Option None of the above: Incorrect because 31 is listed among the options and is the correct value.
Common Pitfalls:
Common mistakes include evaluating the expression left to right without regard to operator precedence, or interpreting the last 3 ÷ 3 as applied to the entire preceding sum. Remember that multiplication and division must be completed first, in sequence, and only then can addition and subtraction be carried out. Keeping to this discipline ensures consistent and correct evaluation of mixed operations.
Final Answer:
The value of 3 × 3 × 3 + 3 + 3 ÷ 3 is 31.
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