What is the sum of greatest 5 - digit number and lowest 5 - digit number ?

Options

A. `199999`
B. `109999`
C. `99991`
D. `900999`

Answer

To solve the problem of finding the sum of the greatest 5-digit number and the lowest 5-digit number, we can follow these steps:

### Step 1: Identify the greatest 5-digit number
The greatest 5-digit number is formed by using the digit 9 in all five places. Therefore, the greatest 5-digit number is:
\[ 99999 \]

### Step 2: Identify the lowest 5-digit number
The lowest 5-digit number is formed by placing the digit 1 in the highest place (ten-thousands) and filling the remaining places with 0. Therefore, the lowest 5-digit number is:
\[ 10000 \]

### Step 3: Add the two numbers together
Now, we will add the greatest 5-digit number and the lowest 5-digit number:
\[ 99999 + 10000 \]

### Step 4: Perform the addition
Let's perform the addition step by step:
- Start from the rightmost digit:
- \(9 + 0 = 9\)
- \(9 + 0 = 9\)
- \(9 + 0 = 9\)
- \(9 + 0 = 9\)
- \(9 + 1 = 10\) (write down 0 and carry over 1)

So, when we add them together:
\[ 99999 + 10000 = 109999 \]

### Final Answer
Thus, the sum of the greatest 5-digit number and the lowest 5-digit number is:
\[ \boxed{109999} \]

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