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# Topic 2 Number Sense

### Number Sense: Addition and Subtraction

Term | Definition |
---|---|

addends | Numbers added together to give a sum. Example: 7 + 5 = 12, 7 and 5 are addends |

sum | The answer when adding two or more addends. Example: 7 + 5 = 12, 12 is the sum |

Commutative (Order) Property of Addition | Numbers can be added in any order and the sum will be the same. Example: 5 + 3 = 3 + 5 |

Associative (Grouping) Property of Addition | Numbers can be grouped in any way and the sum will be the same. Example: (3 + 2) + 4 = 3 + (2 + 4) |

Identity (Zero) Property of Addition | The sum of zero and any number is that number. Example: 0 + 4 = 4 |

difference | The answer when subtracting two numbers. Example: 7 - 2 = 5, 5 is the difference |

fact family | A group of related facts using the same numbers. Example: 5 + 3 = 8, 3 + 5 = 8, 8 - 3 = 5, and 8 - 5 = 3 |

round | Finding a number closest to a specific place value. We use round numbers when we do not use an exact number. Example: 27 rounds to 30 |

estimate | To give a number or answer that tells about how many or how much. |

compatible numbers | Numbers that are easy to add, subtact, multiply, or divide mentally. |

equation | A number sentence that uses an equal sign (=) to show that the value to its left is the same as the value to its right. Example: 6 + 5 = 10 |

Created by:
Third Graders