Solve, using properties/ methods that simplify the calculations:
`455xx9999`

Answer

To solve the problem \( 455 \times 9999 \) using properties that simplify calculations, we can utilize the distributive property. Here’s a step-by-step solution:

### Step 1: Rewrite 9999
We can express \( 9999 \) as \( 10000 - 1 \). This allows us to use the distributive property of multiplication over subtraction.

\[ 9999 = 10000 - 1 \]

### Step 2: Apply the Distributive Property
Now, we can rewrite the multiplication:

\[ 455 \times 9999 = 455 \times (10000 - 1) \]

Using the distributive property, we can distribute \( 455 \) across the subtraction:

\[ 455 \times 9999 = 455 \times 10000 - 455 \times 1 \]

### Step 3: Calculate Each Part
Now we calculate each part:

1. \( 455 \times 10000 = 4550000 \)
2. \( 455 \times 1 = 455 \)

### Step 4: Subtract the Results
Now, we subtract the second result from the first:

\[ 4550000 - 455 \]

### Step 5: Perform the Subtraction
To perform the subtraction, we can align the numbers:

```
4550000
- 455
-----------
4549545
```

Thus,

\[ 455 \times 9999 = 4549545 \]

### Final Answer
The final answer is:

\[ \boxed{4549545} \]

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