# 4. 3 Digit + 2 Digit

Add a 2 digit number to a 3 digit number without regrouping. In this grade, adding by using the standard algorithm should not be the focus. Students should practice addition based on concepts of place value. For example, to add a 2 digit number to a 3 digit number, they can add ones to ones and tens to tens. To understand how this works, they should look at the expanded forms of numbers. For example, 323 + 45 is the same as (300 + 20 + 3) + (40 + 5). They can now group the ones and the tens together to add. It is important for the students to know how a particular method works, rather than just using the method. Adding using place concepts and value concepts will help students make sense of the standard algorithm, when they use it more frequently in the higher grades.

### Common Core Alignment

**2.NBT.7**Add and subtract within 1000, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method. Understand that in adding or subtracting three-digit numbers, one adds or subtracts hundreds and hundreds, tens and tens, ones and ones; and sometimes it is necessary to compose or decompose tens or hundreds.