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Adding a 1-Digit Number to a 2-Digit Number

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Adding a 1-Digit Number to a 2-Digit Number
CCSS.MATH.CONTENT.1.NBT.C.4

Basics on the topic Adding a 1-Digit Number to a 2-Digit Number

Adding 1 Digit Numbers to 2 Digit Numbers

This text will teach you about two-digit numbers and how to do written addition by adding one-digit numbers to two-digit numbers. But first, let’s go over the meaning of one digit numbers and two digit numbers and how to represent them.

Revision – Digits

What is a 1 digit number? Digits in math are the position of numbers. A one digit number is a single number symbol used to represent zero through nine.These numbers (0, 1, 2, 3, 4, 5, 6, 7, 8, and 9) are called one digit numbers because they only have one digit, or number symbol, used to represent them.

When we put two of these number symbols (0, 1, 2, 3, 4, 5, 6, 7, 8, and 9) next to each other, it is called a two digit number. For example, numbers like 12, 34, 56, 78, or 90 are two digit numbers. So when you have a number larger than ten, you have a two-digit number. As you know, numbers can be displayed using a place value chart. Here, the digits are represented by the terms ones and tens. The number 12 for example looks like this when put in a place value chart:

Tens Ones
1 2

For the number 12, there is a 1 in the tens place and a 2 in the ones place.

Adding 2 Digit Numbers to 1 Digit Numbers – Example

Let’s learn more about adding numbers with different digits together and an easy strategy to use for solving these equations! Sometimes we have to add a two digit number and one digit number together. When this happens, always start with the two digit number. Then, add the one digit number to it. The answer to the problem is called the sum.

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There are many ways to add a one digit number to a two digit number, but here we will use a ten frame! Let's use the equation eleven plus three as an example.

First, circle the one digit number, three. Then, fill in the ten frame with three counters.

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Next, start counting-on from the two digit number, eleven, and stop when you reach the last counter which would be fourteen.

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Fourteen is the answer so we write that in the sum position at the end of the equation.

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Adding 2 Digit Numbers to 1 Digit Numbers – Summary

How do you add two digit numbers to one digit numbers? Remember, when adding a one digit number to a two digit number using a ten frame, you should follow these steps:

Step # What to do
1 Start by circling the one digit number.
2 Then, fill in the ten frame with
that number of counters.
3 Next, start counting-on from the
two digit number.
4 Stop when you reach the last counter.
This number is the answer!
  • Start by circling the one digit number.

  • Then, fill in the ten frame with that number of counters.

  • Next, start counting-on from the two digit number.

  • Stop when you reach the last counter. This number is the answer!

Have you practiced yet? On this website, you can also find interactive exercises for adding 1 digit numbers to 2 digit numbers along with worksheets and further activities.

Transcript Adding a 1-Digit Number to a 2-Digit Number

Mr. Squeaks and Imani are at the comic store adding to their collections. They are huge fans of The Adventures of Robo-Rodent, a crime fighting critter who’s part machine, part animal. Mr. Squeaks has thirty-five comics and wants to see how many he will have if he buys five more. Imani has forty-nine and wants to know their total if they add another six. Let's help them figure out how many comics they will have by "Adding a One Digit Number to a Two Digit Number"! A digit is a single number symbol we use to represent zero through nine. These numbers are called one digit numbers because they only have one digit, or number symbol, used to represent them. When we put two of these number symbols next to each other, it is called a two digit number. Sometimes we have to add a two digit number and one digit number together. When this happens, always start with the two digit number. Then, add the one digit number to it. The answer to the problem is called the sum. There are many ways to add a one digit number to a two digit number, but today we will use a ten frame! First, circle the one digit number, three. Then, fill in the ten frame with three counters. Next, start counting-on from the two digit number, eleven and stop when you reach the last counter. Let's count together: eleven, twelve, thirteen, fourteen! Fourteen is the answer! Write it here. Now, let's help Mr. Squeaks figure out how many comics he will have if he adds five more to his collection of thirty-five. First, circle the one digit number, five. Then, fill in the ten frame with five counters. Next, start counting-on from the two digit number, thirty-five. Let's count together: thirty-five, thirty-six, thirty-seven, thirty-eight, thirty-nine, forty! We stopped on forty, so we write it here as the sum. Mr. Squeaks will have forty comics! We can help Imani now! Remember, Imani has forty-nine comics and wants to add another six. What is our first step? First, circle the six. Then, fill in the ten frame with six counters. What happens next? Next, we start counting-on from forty-nine. What number do we end on? We end on fifty-five, so we write it here as the answer. Imani will have fifty-five comics! Before Mr. Squeaks and Imani leave the store, let's remember! Today we learned about adding a one digit number to a two digit number using a ten frame. Start by circling the one digit number. Then, fill in the ten frame with that number of counters. Next, start counting-on from the two digit number. Stop when you reach the last counter. This number is the answer! Look who's coming in just as Imani and Mr. Squeaks are about to leave. It's a bird, it's a plane! No! It's RoboRodent! "Can we get your PAW-tograph?!"

Adding a 1-Digit Number to a 2-Digit Number exercise

Would you like to apply the knowledge you’ve learned? You can review and practice it with the tasks for the video Adding a 1-Digit Number to a 2-Digit Number.
  • Find the sum using the ten frame.

    Hints

    Remember, the sum is the total of both numbers together.

    Solution

    We can find the sum once we count on using the tens frame. The sum is the last number and we write it under the equation.

  • Find the sum by counting on.

    Hints

    Remember, start at the two digit number, and count on using the ten frame.

    Solution

    Mr. Squeaks now has 47 comic books! Thanks Imani!

    We started at 40, then added 7 more using the ten frame. The sum of the comic books is 47.

  • Solve the equation.

    Hints

    Remember, use the ten frame to count up starting at the two digit number.

    Remember, the sum is the last number from counting up.

    Solution

    Imani will have 58 comics! Start at 49, then count up 9. The sum is 58.

  • Fill in the steps to solve the problem.

    Hints

    Remember, identify the one digit number first. Then, add it in the ten frame. Look at this example to help.

    Solution

    When adding a one digit number to a two digit number:

    First we identify the one digit number by circling it.

    Second, we fill in the ten frame.

    Third, we count on.

    Fourth, we find the sum.

  • Identify one digit and two digit numbers.

    Hints

    Remember, one digit numbers only have one number.

    Solution

    One digit numbers only have one digit and were highlighted in green.

    Two digit numbers have two digits and were highlighted in purple.

  • Complete and solve the problem.

    Hints

    Remember, start at the two digit number, and count on.

    Solution

    Imani now has 19 comic books in total. We start by counting up 6 from 13. Using the ten frame, we count until 19. 19 is our answer.