Round 999.999 to the nearest tenth

Answer: 1000

Reasoning:

For the number 999.999, the 0.9 is the tenth's digit.

Since the next number is 5 or greater, we round the 0.9 up. Now 0.9 rounded up is 1, so that takes away the decimals and adds one to the ones place value.

Since we are adding 1 to 9, it becomes 10, meaning the following 9 becomes a ten as well.

All said and done, it becomes 1000 from the rounding.