# North Carolina - Grade 1 - Math - Numbers and Operations in Base Ten - Mental Math - NC.1.NBT.5

### Description

Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.

• State - North Carolina
• Standard ID - NC.1.NBT.5
• Subjects - Math Common Core

### Keywords

• Math
• Numbers and Operations in Base Ten

## 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.