Answer:
3.456 rounded to the nearest tenth would be 3.5.
Explanation:
To round we look at the next smallest place value (i.e. the number to the right of the place you're rounding to).
If the number to the right is 5 or larger, you increase the number you're rounding to by (+1).
If the number to the right is smaller than 5, you keep the number you're rounding to the same.
Hope I helped! :)