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Balance simple subtraction equations

Understanding simple subtraction equations means interpreting the equal sign as a relationship between two quantities of the same value, and determining a missing number so equations such as 9−4=59-4=5, 9−□=59-\square=5, or 9−4=8−39-4=8-3 are true. Within 20, subtraction is connected to taking away, comparing, part–whole relationships, and the inverse relationship with addition, using number lines or models; multi-step equations, negative numbers, and generalized algebraic transformations are beyond this scope.

Detailed Explanation: Balance simple subtraction equations

An equation is like a balanced scale: the expression on the left must have the same value as the number on the right.

To solve a subtraction equation, think: “What number do I take away?”

Example:

9−□=59-\square=5
  1. Start with 99.
  2. Count backward until you reach 55:
    9→8→7→6→59 \to 8 \to 7 \to 6 \to 5
  3. You counted back 44 steps, so the missing number is 44.
  4. Check your answer:
9−4=59-4=5

The equation is true, so:

9−□=5and□=4\boxed{9-\square=5 \quad \text{and} \quad \square=4}

Learn by doing: Balance simple subtraction equations

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    Subtraction - Missing Value, 1 Digit, 1 Number

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