number sentence — Definition, Formula & Examples
A number sentence is a mathematical statement written with numbers and symbols (such as +, −, ×, ÷, =, <, or >) that is either true or false. For example, 3 + 4 = 7 is a true number sentence, and 5 > 9 is a false number sentence.
A number sentence is a complete mathematical statement that expresses a relationship between numerical expressions using an equality sign (=) or an inequality sign (<, >, ≤, ≥). It must be evaluable as either true or false.
How It Works
A number sentence has three parts: a left side, a symbol in the middle, and a right side. The symbol tells you what relationship to check. If you see an equals sign, both sides must have the same value for the sentence to be true. If you see a greater-than or less-than sign, you compare the two sides to decide if the statement is true or false. Number sentences can use any operation — addition, subtraction, multiplication, or division.
Worked Example
Problem: Is the number sentence 12 − 5 = 7 true or false?
Step 1: Find the value of the left side.
Step 2: Compare the left side to the right side. The left side equals 7 and the right side equals 7. Since both sides match, the number sentence is true.
Answer: The number sentence 12 − 5 = 7 is true.
Why It Matters
Number sentences are the bridge between counting and algebra. When you write 8 + ? = 15 and solve for the missing number, you are already doing the same thinking that algebra requires with variables like .
Common Mistakes
Mistake: Writing an incomplete expression like 3 + 4 and calling it a number sentence.
Correction: A number sentence must include a comparison symbol (=, <, >) to make a complete statement. 3 + 4 is an expression; 3 + 4 = 7 is a number sentence.