  # North Carolina - Grade 1 - Math - Operations and Algebraic Thinking - Adding and Subtracting within 20 - NC.1.OA.4,6,9

### Description

NC.1.OA.4 Solve an unknown-addend problem, within 20, by using addition strategies and/or changing it to a subtraction problem. NC.1.OA.6 Add and subtract, within 20, using strategies such as counting on, making ten, decomposing a number leading to a ten, using the relationship between addition and subtraction, using a number line, and creating equivalent but simpler or known sums. NC.1.OA.9 Demonstrate fluency with addition and subtraction within 10.

• State - North Carolina
• Standard ID - NC.1.OA.4,6,9
• Subjects - Math Common Core

### Keywords

• Math
• Operations and Algebraic Thinking

## More North Carolina Topics Represent and solve word problems that call for addition of three whole numbers whose sum is less than or equal to 20, by using objects, drawings, and equations with a symbol for the unknown number. Using concrete models or drawings, strategies based on place value, properties of operations, and explaining the reasoning used, add, within 100, in the following situations: • A two-digit number and a one-digit number • A two-digit number and a multiple of 10 Subtract multiples of 10 in the range 10-90 from multiples of 10 in the range 10-90, explaining the reasoning, using: • Concrete models and drawings • Number lines • Strategies based on place value • Properties of operations • The relationship between addition and subtraction Order three objects by length; compare the lengths of two objects indirectly by using a third object. Tell and write time in hours and half-hours using analog and digital clocks.

## Here is the skill that North Carolina requires you to master

• State Standards North Carolina’s Standard Course of Study
• Subject Math
• Topic Name Adding and Subtracting within 20
• Standard ID NC.1.OA.4,6,9
• Description
NC.1.OA.4 Solve an unknown-addend problem, within 20, by using addition strategies and/or changing it to a subtraction problem. NC.1.OA.6 Add and subtract, within 20, using strategies such as counting on, making ten, decomposing a number leading to a ten, using the relationship between addition and subtraction, using a number line, and creating equivalent but simpler or known sums. NC.1.OA.9 Demonstrate fluency with addition and subtraction within 10.  