Subtrahend

Definitionnoun

What is a subtrahend in math?

The subtrahend is the number being subtracted: the number written after the minus sign. In 12 − 5 = 7, the subtrahend is 5. It is taken away from the minuend (12) to leave the difference (7). To find a missing subtrahend, subtract the difference from the minuend: 12 − 7 = 5.

In Spanish
sustraendo
Also called
number being subtracted, second number in a subtraction
How to say it
SUB-truh-hend
Grade level
K-5
Grade 1Grade 2Grade 3CCSS 1.OA.B.4CCSS 1.OA.D.8TABEASVAB

Subtrahend in a picture

Subtrahends of 5, 9 and 12 taken from 12Three rows of 12 dots. In the first row 5 dots are crossed out, leaving 7. In the second, 9 are crossed out, leaving 3. In the third, all 12 are crossed out, leaving 0. The crossed-out dots are the subtrahend and the dots left are the difference.Same minuend, different subtrahends12 − 5= 712 − 9= 312 − 12= 0Bigger subtrahend → smaller differencecrossed-out dots = the subtrahendgreen dots left = the difference
The subtrahend is how many you take away. With the minuend fixed at 12, subtrahends of 5, 9 and 12 leave 7, 3 and 0.

Formal definition and notation

In a subtraction a − b = c, the number b is the subtrahend. It is the unique number for which c + b = a, so b = a − c. Subtracting b is the same as adding its opposite: a − b = a + (−b). For a fixed minuend, a larger subtrahend gives a smaller difference.

Symbol Read it as Meaning
a − b a minus b b, after the minus sign, is the subtrahend
a + (−b) a plus the opposite of b the same value: subtracting a subtrahend equals adding its opposite

Key facts

  • The name comes from Latin and means “the thing to be subtracted”.
  • The subtrahend sits right after the minus sign: in 45 − 18, it is 18.
  • A subtrahend of 0 changes nothing: 37 − 0 = 37.
  • In word problems, “take away”, “less than” and “subtract … from” point to the subtrahend: “6 less than 20” is 20 − 6, with subtrahend 6.
  • A negative subtrahend increases the result: 9 − (−4) = 9 + 4 = 13.

Missing subtrahend rule

Missing subtrahend rule
subtrahend = minuend − difference
minuend
the starting number, before the minus sign
difference
the result, after the equals sign

For 80 − □ = 54: subtrahend = 80 − 54 = 26. Check: 80 − 26 = 54.

Try it: subtrahend as a distance

Interactive

Put the green point on the minuend and the blue point on the difference. The distance between them is the subtrahend. Try a minuend of 15 and a difference of 6.

This interactive needs JavaScript. The worked examples below show the same ideas step by step.

Subtrahend examples, step by step

Example 1: Name the subtrahend

Warm-up

What is the subtrahend in 73 − 28 = 45?

  1. The subtrahend is the number right after the minus sign: 28.
  2. Check: 73 − 45 = 28.

Answer: The subtrahend is 28.

Example 2: Find a missing subtrahend

Core

Solve 140 − □ = 86.

  1. The box is the subtrahend; 140 is the minuend and 86 is the difference.
  2. Subtrahend = 140 − 86.
  3. 140 − 86 = 54.
  4. Check: 140 − 54 = 86.

Answer: The missing subtrahend is 54.

Example 3: A negative subtrahend

Test-style

The temperature at noon was 5 degrees C. At midnight it was −8 degrees C. Write the change from midnight to noon as a subtraction and evaluate it.

  1. Change = later value − earlier value = 5 − (−8). The subtrahend is −8.
  2. Subtracting a negative is adding its opposite: 5 + 8.
  3. 5 + 8 = 13.

Answer: The temperature rose 13 degrees Celsius.

Common mistakes

✗ Mistake“7 less than 30” means 7 − 30.
✓ InsteadIt means 30 − 7 = 23. The 7 is the subtrahend.

“Less than” reverses the spoken order: the number before “less than” is the one taken away.

✗ MistakeFor 50 − □ = 18, add: 50 + 18 = 68.
✓ InsteadSubtract: 50 − 18 = 32. Check: 50 − 32 = 18.

The subtrahend is a part of the minuend, so it must be smaller than 50 here. Adding gives a number larger than the starting amount.

✗ Mistake10 − (−3) = 7
✓ Instead10 − (−3) = 10 + 3 = 13.

Taking away a negative subtrahend removes a debt, so the result goes up.

Not to be confused with

Subtrahendvs.Minuend

The minuend comes first and is the number you start with; the subtrahend comes second and is taken away. In 30 − 12: minuend 30, subtrahend 12.

Subtrahendvs.Difference

The difference is the answer, not the amount removed. In 30 − 12 = 18, the subtrahend is 12 and the difference is 18.

Quick check: 3 questions

Question 1 of 3

In 250 − 75 = 175, which number is the subtrahend?

Show answer and explanation

Answer: D. 75 is after the minus sign, so it is the subtrahend. 250 is the minuend, 175 is the difference, and 325 adds the first two numbers.

Question 2 of 3

Find the subtrahend: 64 − □ = 39.

Show answer and explanation

Answer: A. 64 − 39 = 25, and 64 − 25 = 39. 103 adds the numbers; 35 and 15 are regrouping slips.

Question 3 of 3

Which phrase has a subtrahend of 9?

Show answer and explanation

Answer: C. “9 fewer than 31” means 31 − 9, so 9 is taken away. In the other three phrases 9 is the starting number (the minuend): 9 − 4, 9 − 2, 9 − 1.

Subtrahend: frequently asked questions

How do you remember minuend and subtrahend?

The subtrahend shares its start with “subtract”: it is the number that gets subtracted, after the minus sign. The minuend is the number before it, the one that is made smaller. In 9 − 2 = 7, 9 is the minuend, 2 is the subtrahend and 7 is the difference. Saying “minuend minus subtrahend equals difference” keeps the order.

What happens when the subtrahend is bigger than the minuend?

The difference is negative. For example, 8 − 13 = −5: you go 13 steps left from 8 on a number line and land 5 below zero. In grades 1 to 5, problems usually keep the subtrahend smaller, but with integers any subtrahend is allowed.

Practice and tools

Sources

  1. Common Core State Standards, Grade 1 Operations and Algebraic Thinking (1.OA.B.4, 1.OA.D.8)
  2. OpenStax, Prealgebra 2e, 1.3 Subtract Whole Numbers
  3. OpenStax, Prealgebra 2e, 3.3 Subtract Integers

Updated November 2026·Reviewed by the Effortless Math team·Standards: CCSS 1.OA.B.4, CCSS 1.OA.D.8

Cite this entry

Effortless Math Team. “Subtrahend.” Effortless Math Dictionary. Updated November 2026. https://www.effortlessmath.com/math-dictionary/subtrahend/

Flashcard

TermSubtrahendthe 5 in 12 − 5 = 7
DefinitionThe number being subtracted, after the minus sign. In 12 − 5 = 7, the subtrahend is 5. Missing subtrahend: minuend minus difference.
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