`18!+19!`

Answer

To solve the expression \( 18! + 19! \), we can follow these steps:

### Step 1: Rewrite \( 19! \) in terms of \( 18! \)
We know that \( 19! \) can be expressed as:
\[ 19! = 19 \times 18! \]

### Step 2: Substitute \( 19! \) in the original expression
Now, we can substitute this back into the original expression:
\[ 18! + 19! = 18! + 19 \times 18! \]

### Step 3: Factor out \( 18! \)
Next, we can factor out \( 18! \) from both terms:
\[ 18! + 19 \times 18! = 18!(1 + 19) \]

### Step 4: Simplify the expression inside the parentheses
Now, simplify the expression inside the parentheses:
\[ 1 + 19 = 20 \]

### Step 5: Write the final expression
Now we can write the final expression:
\[ 18! + 19! = 18! \times 20 \]

### Final Answer
Thus, the value of \( 18! + 19! \) is:
\[ 18! \times 20 \]

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