# ARE YOU TEACHING HOW TO SUBTRACT WHOLE NUMBERS?

Last week we talked about teaching how to add whole numbers. That standard was CC.4.NBT.A.2 - Read and write multi-digit whole numbers using base-ten numerals, number names, and expanded form. Compare two multi-digit numbers based on meanings of the digits in each place, using >, =, and < symbols to record the results of comparisons. Click here to read that previous post. This week's post is about teaching how to subtract whole numbers. The standard is CC.4.NBT.B.4 - Fluently add and subtract multi-digit whole numbers using the standard algorithm.

If you are new to my blog, I love math and have had many years teaching it. I love small group teaching, but for small groups to run smoothly, your math centers, your math workstations, have to have activities and worksheets that the students can do without you. To that end, I've created many center games, task cards and worksheet bundles to help you in my TpT store. Join me every Wednesday for my 4th grade math posts.

Subtracting numbers with more than one-digit requires an understanding of place value. The place value of a digit is the value based on its position within the number. In the number 816, the 8 is in the hundreds place, the 1 is in the tens place, and the 6 is in the ones place. To see more about reviewing place value, click here or here. Your students have been working on understanding addition and subtraction since kindergarten, in fourth grade, they move away from manipulatives and work towards using the standard algorithm to perform fast and accurate multi-digit addition and subtraction.

LESSON:
Start by telling your students that real world math often gives us many examples of when we need to have a solid understanding of place value, and subtracting large numbers can lead to many mistakes. Yes, we all have calculators on our phones in this day and age, but students still need this life skill. Even the mental math of rounding the numbers, then subtracting them to get a ball park answer is important.

For Example:
Employees at a large pool supply company had 14,625 buckets of chlorine for sale on June 1st. On June 30th they only had 11,389 buckets left in stock. How many buckets of chlorine did they sell in June? Estimate first and then solve.

Extend this example for a high group:
If the company wants to keep 18,000 buckets of chlorine on hand at the start of each month, how many buckets will they need to order?

Give your students a few more real world examples to practice rounding numbers and subtracting them mentally.
{To make this a little more engaging, let half the class solve it on white boards at the same time to check the mental math of the other half of the class. Then swap.}

1. Anna's class is raising money to buy books for their school library. Their goal is \$27,000. They have already raised \$24,016. How much more do they need to collect to reach their goal? {Estimate - is \$30,000 a reasonable answer?}

2. A cruise ship needs 17,500 keepsake cups, one for each day, for their 2,500 passengers. The cup company made a mistake and did not send enough. If they only sent 15,700 cups, how many more cups will the cruise ship need to get?

3. The store sold 657,328 pencils in August. The store then sold 423,998 pencils in September. How many more pencils did they sell in August?

Once you have worked on the mental math of these problems, it is time to put pencil to paper, or marker to marker board, and work out the subtraction of multi-digit whole numbers.

I Love Graph Paper for Place Value!

In addition to getting graph paper from the store, you can also print some out for your boys and girls for free, at this web site, Free Online Graph Paper.

I recommend several examples together on the board, or on your digital camera. Model lining them up, one digit at a time on the graph paper, so that they look like this, to help with lining up the place value.

1. 65,132 - 23,157 =
2. 84,916 - 45,637 =
3. 214,057 - 118,457 =
4. 428,661 - 374,126 =
5. 788,545 - 675,616 =

1. 41,975
2. 39,279
3. 95,600
4. 54,535
5. 112,929

Then, taking it up a step, students need to transition from the graph paper to writing the problems themselves. I always love teaching them to make a quick chart on a sideways piece of notebook paper.... first let them use different colored markers, besides the fact that it's fun, the colors help them have a mental imprint on their brain after they have practiced, helping them to remember to line these problems up correctly. Later, they can just use their pencil. Teaching them to make a quick chart like this one is one more thing that your fourth graders can add to their tool box of math tricks. During standardize testing time, this is an excellent trick/tip for your students to remember. For a different tip, click here to see the addition of whole numbers post that can also work for subtraction.

A Quick Chart to Add to Your Students' Mental Math Tool Box

BE ON THE LOOK OUT FOR THIS STUDENT ERROR:
Many times students will line the problem up correctly, but then just subtract the lesser digit for the greater digit. An example would be 92 - 67 = The student would subtract the 2 from the 7 in the ones column and then the 6 from the 9 in the tens column. Their answer would be 35 instead of 25. Catch it quick enough and a little bit of remediation will fix this error.

EXTENDING THE LESSON:
Rework some of the above problems in student pairs with white boards and calculators. The students can work a problem, trade whiteboards and double check each other's work with the calculator. They love working in pairs in 4th grade and calculator skills are a well needed life skill too!

I've created a center game resource and a task card resource, as well as a discounted bundle to help you introduce, reinforce, remediate and spiral review for how to subtract whole numbers.

Standard: CC.4.NBT.B.4 - Fluently add and subtract multi-digit whole numbers using the standard algorithm.

This bundle has task cards and center games for 4th Grade Math Subtract Whole Numbers. You will love how easy it is to prepare this easy to prep bundle for your math class. Perfect for small groups, read the room, centers, scoot, tutoring, Around the World whole class game, homework, seat work, so many ways to use these task cards that the possibilities are endless. Your students will enjoy reviewing important skills with the center games! Perfect for an assessment grade for the week or for a substitute teacher day!

Once your students are used to the expectations of using center games and task cards, your math skills math center can run all year with different skills from my TpT Store.

This Subtract Whole Numbers Center Game and Task Cards Bundle Contains the Following Resources:

The 15 Page Subtract Whole Numbers Bundle Includes:

The 5 Page Subtract Whole Numbers Center Game Includes:

→ 3 Pages of Center Game Cards

→ 2 Different Types of Center Game Folder Cover

The 10 Page Subtract Whole Numbers Task Card Resource Includes:

→ 28 Task Cards in color

→ 1 Printable Recording Worksheet

→ 1 Task Card Folder Cover

Subtract Whole Numbers Task Cards, Recording Sheet, and Center Game are Perfect for...

• Remediation and RTI groups
• Substitute teacher folders
• Scoot Game! Keep them all up and moving!
• Math Workstations
• Indoor recess
• Morning work
• Emergency sub tubs
• Morning Math buckets
• Math centers
• Early morning students
• After school tutoring
• Parent Math Nights
• And so much more!

Enjoy this 4th Grade Math Subtract Whole Numbers Task Cards and Center Game Bundle in your Math Center!

When it comes to the ease of prepping this Subtract Whole Numbers Center Game and Task Cards, all pieces are rectangular and easy for you or a parent volunteer to cut on a paper slicer. No need to cut around a cute turkey or round pumpkin task card, just rectangles with frames and the math problems, perfect for fourth graders!

The 5 Page Subtract Whole Numbers Center Game of This Bundle Includes:

→ 3 Pages of Center Game Cards

→ 2 Different Types of Center Game Folder Cover

→ Page 1 - Full Color Center Game Folder Cover

→ Page 2 - Minimal Color {Save Your Ink} Center Game Folder Cover

→ Page 3 to 5 - 3 Pages of Quick and Easy to Prep Center Game Cards.

This 10 Page Subtract Whole Numbers Task Card of This Bundle Resource Includes:

→ 28 Task Cards in color

→ 1 Printable Recording Worksheet

→ 1 Task Card Folder Cover

→ Page 1 - Task Card Folder Cover

→ Page 2 to 8 - 28 "Find the difference." Subtracting Whole Numbers Task Cards

→ Page 9 - Recording Sheet for Task Cards 1 to 28.

→ Page 10 - Answer Key / Student Self-Checking Page.

Common Core State Standard

CCSS.MATH.CONTENT.4.NBT.B.4

Fluently add and subtract multi-digit whole numbers using the standard algorithm.

This Subtract Whole Numbers Task Card and Center Game Bundle is ALSO Part of the Following Bundles:

The Center Game and Task Cards are so easy to prep, it is perfect to give to a parent volunteer who is asking, "How can I help?" or your PTA / PTO volunteer room. It is also terrific for an Emergency Substitute Tub, Folder or Binder!

Terrific for an Emergency Sub Tub, Math Centers, Small Group Work, Remediation RTI or Homework!

Have a great week Friends!