To round 963803.75319 to the nearest thousandth, we focus on the thousandths place, which is the third digit to the right of the decimal.

1. The thousandths digit is 3.
2. The next digit to the right (the ten-thousandths place) is 1.
3. Since 1 is less than 5, we do not round up.

Thus, 963803.75319 rounded to the nearest thousandth is 963803.753.

Would you like further clarification on rounding methods or more examples?

Here are some related questions:

1. How would you round 963803.75319 to the nearest hundredth?
2. What is the process for rounding large numbers to the nearest hundred?
3. Can you round 963803.75319 to the nearest whole number?
4. How does rounding to different decimal places impact accuracy?
5. How would you explain the difference between rounding and truncating?

Tip: When rounding a number, always check the digit immediately after the place you're rounding to.