mikayla evaluated the expression $0.86 \times 23.4$ using the steps shown below.

$\begin{array}{r} 0.86 \\ \times 23.4 \\ \hline 344 \\ 2580 \\ +17200 \\ \hline 201.24 \end{array}$

which best explains mikaylas error?

mikayla added the whole numbers incorrectly.
mikayla multiplied the whole numbers incorrectly.
mikayla moved the decimal incorrectly.
mikaylas answer should have been a whole number.

Question

mikayla evaluated the expression $0.86 \times 23.4$ using the steps shown below.

$\begin{array}{r} 0.86 \\ \times 23.4 \\ \hline 344 \\ 2580 \\ +17200 \\ \hline 201.24 \end{array}$

which best explains mikaylas error?

mikayla added the whole numbers incorrectly.
mikayla multiplied the whole numbers incorrectly.
mikayla moved the decimal incorrectly.
mikaylas answer should have been a whole number.

Accepted Answer

{ "quality": "clear", "question_count": 1, "skills_matched": [ "step_cot", "multiple_choice_formatter", "explain_then_answer", "tutor", "mastery_adaptive_brevity" ], "needs_drawing": false, "concepts_used": [ "Decimal Multiplication", "Decimal Places" ], "new_concepts": [], "current_concepts": [ "Decimal Multiplication", "Decimal Places", "Multi-Digit Multiplication" ] } ## Analyze the multi-digit multiplication Using the *Multi-Digit Multiplication* knowledge point $$ \begin{aligned} &86 \times 234 = 20124\ &4 \times 86 = 344\ &30 \times 86 = 2580\ &200 \times 86 = 17200\ &344 + 2580 + 17200 = 20124 \end{aligned} $$ ## Determine the correct decimal placement Using the *Decimal Places* and *Decimal Multiplication* knowledge points $$ \begin{aligned} &\text{Decimal places in } 0.86: 2\ &\text{Decimal places in } 23.4: 1\ &\text{Total decimal places required}: 2 + 1 = 3\ &20124 \times 10^{-3} = 20.124 \end{aligned} $$ ## Identify Mikayla's error Using the *Decimal Multiplication* knowledge point $$ \begin{aligned} &\text{Mikayla's result}: 201.24\ &\text{Correct result}: 20.124\ &\text{Error}: \text{Placed the decimal point after two decimal places instead of three.} \end{aligned} $$

Mikayla added the whole numbers incorrectly.

Mikayla multiplied the whole numbers incorrectly.

Mikayla moved the decimal incorrectly.

Mikayla's answer should have been a whole number.

{ "subject": "Mathematics", "question_type": "Multiple Choice", "knowledge_point": [ "Mathematics", "Algebra", "Decimal Multiplication" ] }

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QUESTION IMAGE

Question

Explanation:

Analyze the multi-digit multiplication

Determine the correct decimal placement

Identify Mikayla's error

Answer: