Write the following divisions as fractions.
a. `537 div 1000 =`________

Answer

To convert the division of 537 by 1000 into a fraction, we follow these steps:

### Step-by-Step Solution:

1. **Identify the Division**: We start with the division statement, which is \( 537 \div 1000 \).

2. **Write as a Fraction**: To express this division as a fraction, we place the numerator (the number being divided) over the denominator (the number we are dividing by). Thus, we write:
\[ \frac{537}{1000} \]

3. **Check for Simplification**: Next, we check if the fraction can be simplified. We look for any common factors between 537 and 1000. The factors of 537 are 1, 3, 179, and 537, while the factors of 1000 are 1, 2, 4, 5, 8, 10, 20, 25, 40, 50, 100, 125, 200, 250, 500, and 1000. Since there are no common factors other than 1, the fraction cannot be simplified further.

4. **Final Answer**: Therefore, the final answer is:
\[ \frac{537}{1000} \]