Subtraction By 1

Overview

We can use subtraction to find the difference between a big group and a small group. Subtraction can tell us how many are left.

Subtraction helps us to separate two groups and find the difference!

Many times we have a group of objects and we want to take one away from the group.

For example:

There are 3 cats, but 1 cat is crossed out.
We can SUBTRACT to find out how many ARE LEFT.
This will give us the DIFFERENCE.

When we SUBTRACT 3 minus 1, we have 2 LEFT.
We say: THREE minus ONE equals TWO.
We write it like this:  3 – 1 = 2

Let’s look at another problem!

There are 6 trucks, but 1 truck is crossed out.
We can SUBTRACT to find out how many ARE LEFT.
This will give us the DIFFERENCE.

When we SUBTRACT 6 minus 1, we have 5 LEFT.
We say: SIX minus ONE equals FIVE.
We write it like this:  6 – 1 = 5

Simple! Let’s look at another problem together.

This time we will subtract smiley faces.
We are SUBTRACTING to find out how many are left.

We can see that there were four smiley faces to start with. One of the smiley faces is now gone.
When we SUBTRACT 4 minus 1, we have 3 left.
We say: FOUR minus ONE equals THREE.
We write it like this:  4 – 1 = 3

Are you ready to try another problem that involves subtracting by 1?

In this example, we are subtracting the number  1 from the number  8.
The first number in the subtraction sentence is called the MINUEND.
The second number in the subtraction sentence is called the SUBTRAHEND.

This problem reads as  8 – 1 = 7.

When the SUBTRAHEND 1 is subtracted from the MINUEND  8, we get a DIFFERENCE of  7.

When we want to find what ONE LESS is in a group of objects, we can remember that the DIFFERENCE will be the number that comes BEFORE when we are counting.

5 – 1 =

For example, 5 – 1 = 4. We also know that when we count, the number that comes before  5 is the number  4. This can help us to subtract quickly and correctly when subtracting 1 from a group.

Here is another example. When we want to find what ONE LESS is in a group of objects, we can remember that the DIFFERENCE will be the number that comes BEFORE when we are counting.

11 – 1 =

For example, 11 – 1 = 10. We also know that when we count, the number that comes before 11 is the number 10. This can help us to subtract quickly and correctly when subtracting 1 from a group.

You’re doing an amazing job! Now, let’s go ahead and review some key words that relate to subtraction. When you see these words in a problem, they should hint to you that subtraction is involved.

Writing down these keywords above is a great way to remember these important words! Here’s a word problem dealing with “Subtracting by 1”.

In the problem, we start with 9 bananas. The key words ARE LEFT tell us to subtract.

ONE banana is eaten from the group. We can subtract to find the DIFFERENCE.

9 – 1 = 8 bananas

Now, let’s practice!

Practice Question 1

Find the difference to solve.

REVEAL THE ANSWER

Practice Question 2

Solve the subtraction problem below.

REVEAL THE ANSWER

Practice Question 3

Use the key words to help you solve.

REVEAL THE ANSWER

Practice Question 4

Find out how many cupcakes are left.

REVEAL THE ANSWER

Practice Question 5

Solve by subtracting.

REVEAL THE ANSWER

You are seriously amazing! Now let’s put this to the test and take the quiz below where you will practice subtracting by 1.