A number sentence is a mathematical sentence made up of numbers and symbols, such as addition, subtraction, multiplication, and division. It is used in primary level mathematics teaching in the US, Canada, UK, Australia, New Zealand, and South Africa. Number sentences are used to introduce students to notions of structure and elementary algebra prior to a more formal treatment of these concepts. They are also used to provide flexibility to solve a problem as compared to basic algorithms. A number sentence without unknowns is equivalent to a logical proposition expressed using the notation of arithmetic. Examples of number sentences include:

• 83 + 19 = 102 (valid and true)
• 1 + 1 = 3 (valid but false)
• 3 + 6 < 10 (valid and true)
• 3 + 9 > 11 (valid and true)

In Year 1, children start learning how to write addition and subtraction number sentences. In Year 2, they start to write number sentences for multiplication and division. Teachers may show children a word problem and then ask them to write the number sentence that goes with it. Children may also come across number sentences with gaps in them.