Find the value of `:`
18.5-6.79

Answer

To solve the problem \( 18.5 - 6.79 \), we will follow these steps:

### Step 1: Align the Numbers
First, we need to align the numbers by their decimal points. This helps us keep track of the digits correctly.

```
18.50
- 6.79
```

### Step 2: Prepare for Subtraction
Notice that we can add a zero to \( 18.5 \) to make it \( 18.50 \) for easier subtraction. Now we have:

```
18.50
- 6.79
```

### Step 3: Subtract the Decimal Part
We start by subtracting the digits after the decimal point.

- From \( 0 \) (in \( 18.50 \)) we cannot subtract \( 9 \) (in \( 6.79 \)), so we need to borrow from the \( 5 \) (in \( 18.50 \)).
- Borrowing makes the \( 0 \) become \( 10 \), and the \( 5 \) becomes \( 4 \).

Now we can subtract:

```
10 - 9 = 1
```

### Step 4: Subtract the Whole Number Part
Now we move to the whole number part. We have:

```
4 (after borrowing) - 7 = -3
```

Since we cannot subtract \( 7 \) from \( 4 \), we need to borrow from the \( 1 \) (in \( 18.50 \)), which makes it \( 0 \) and adds \( 10 \) to the \( 4 \).

Now we can do the subtraction:

```
14 - 7 = 7
```

### Step 5: Final Subtraction
Now we have:

- From \( 0 \) (after borrowing) we have \( 0 - 0 = 0 \).
- From \( 1 \) we have \( 1 - 0 = 1 \).

Putting it all together, we get:

```
18.50
- 6.79
--------
11.71
```

### Final Answer
The value of \( 18.5 - 6.79 \) is \( 11.71 \).

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