Adding 3-Digit Numbers

3 Digit Addition

Three-digit numbers are integral in various mathematical calculations and daily applications. If you're looking for resources and strategies for teaching 3 digit addition to help your child or student with 3 digit column addition, you've come to the right place! We offer a variety of tools and tips to make learning 3-digit addition a breeze. Read our educational text about 3 digit number addition, refer to the addition 3 digit numbers video (featuring 3-digit addition no regrouping and 3 digit addition with regrouping) and apply your knowledge by using our 3 digit addition worksheets including 3 digit addition word problems.

What Are Three-Digit Numbers? – Introduction

Three-digit numbers range from 100 to 999.

Place value is crucial when working with three-digit numbers, as it informs us of a digit's value. Recognising the hundreds, tens and ones place is vital for performing calculations like addition of 3 digit numbers correctly. Let’s have a look at the number 367 in a place value chart. The digits are placed in the hundreds (H), tens (T) and ones place (O):

Foundational Steps to Add Three-Digit Numbers

Once pupils understand three-digit numbers, they can begin learning how to add them. There are essential steps to simplify the process. Three-digit numbers can be difficult to add, so always use a place value chart or use a standard written method to add three-digit numbers. Look at the following steps on how to solve 3 digit addition.

1. Prepare for your calculation

Write down the numbers in a standard written format, aligning digits according to their place value.

2. Always start with the ones place

Begin by adding the digits in the ones place. If the sum is a two-digit number, write down the digit in the ones place and carry over the ten to the tens place.

3. Move on to adding tens

Once you added the unit digits, move on to adding the digits in the tens place. Do not forget to also add any numbers that you carried over from adding the unit digits. If the sum is a two-digit number, write down the unit and carry over the ten to the hundreds place.

4. Move on to adding hundreds

Once you added the digits in the tens place, move on to adding the digits in the hundreds place. Do not forget to also add any numbers that you carried over from adding the tens digits. If the sum is a two-digit number, write down the sum in the hundreds and thousands place.

Step-by-Step Guide to Three-digit Addition with Carrying Over

Let’s look at the example equation and do it together, step by step. Let’s complete 391 + 139.

1. Prepare for your calculation

Write down the first number 391, and right underneath it 139, in a standard written format. Align digits according to their place value - make sure that 9 is under 1, 3 under 9 and 1 under 3. See the example below:

2. Always start with the ones place

Begin by adding the digits in the ones place. In this case, we will add 9 and 1. As you know, the sum of these two digits is 10. This means that you will have to write down 0 in the ones place and carry 1 ten over.

3. Move on to adding tens

Once you have added the unit digits, move on to adding the digits in the tens place. Here we will need to add 3 tens and 9 tens. However, let’s not forget that there is one more ten that we carried over from the units place. In this case, 3 plus 9 plus 1 equals 13. As this sum is over 10, we will have to carry over again. See the example below:

4. Move on to adding hundreds

Once you have added the digits in the tens place, move on to adding the digits in the hundreds place. Here we add 1 hundred and 3 hundred, their sum equals 4 hundred. But do not forget to also add the 1 hundred we carried over from the tens column! Write the digit 5 in the hundreds place. Well done, you have added two three-digit numbers and their sum is 530 - five hundred and thirty. Look at the representation below:

Adding Three-Digit Numbers – Common Mistakes

Common errors include forgetting to carry over or carrying over incorrect values. Also, pay attention to zeros in the ones or tens place. It is important to never skip them and always remember to keep them as place value holders. Practice and attention to detail can help avoid these mistakes.

Adding Three-Digit Numbers – Conclusion

Mastering the addition of three-digit numbers is essential for students, as it lays the groundwork for more advanced mathematical concepts and applications. With understanding, practice and the use of available resources, students can efficiently and accurately add three-digit numbers. Consistent practice and engagement with various learning tools and materials will facilitate mastery of this fundamental skill.

For further 3-digit addition practice, have a look at our addition 3-digit numbers worksheets featuring 3-digit addition word problems. We also have 3 digit addition interactive exercises, 3 digit addition games and 3 digit addition story problems.

Adding Three-Digit Numbers – Frequently Asked Questions