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Find missing values in subtraction equations

Understanding missing values in subtraction equations involves interpreting the unknown as the minuend, subtrahend, or difference and using the inverse relationship between subtraction and addition to determine it. The reasoning applies to whole numbers through the millions, including multi-digit calculations with regrouping, and connects equations, place-value notation, and bar models; solutions remain whole numbers, without extending to negative numbers or generalized algebraic equations.

Detailed Explanation: Find missing values in subtraction equations

A subtraction equation has three parts:

  • Minuend: the number being subtracted from
  • Subtrahend: the number being subtracted
  • Difference: the answer

To find a missing number, use the inverse operation: addition.

Example

Find the missing number:

□−2,786=5,439\Box - 2{,}786 = 5{,}439

The missing number is the minuend. To find it, add the subtrahend and the difference:

2,786+5,4392{,}786 + 5{,}439

Add by place value:

2,786+5,4398,225\begin{array}{r} 2{,}786\\ + 5{,}439\\ \hline 8{,}225 \end{array}

So, the missing number is:

8,225\boxed{8{,}225}

Check your answer by putting it back into the subtraction equation:

8,225−2,786=5,4398{,}225 - 2{,}786 = 5{,}439

The equation is correct, so the missing number is 8,225\boxed{8{,}225}.

Learn by doing: Find missing values in subtraction equations

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    Subtraction - Missing Value, 3 Digit, 2 Numbers

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