# 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:

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!

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