Autumn collected 129 seashells at the beach. What is 129 rounded to the nearest ten?

If you rounded off 129 to the nearest ten the answer would be 130

To round this to the nearest ten, find the ten position and then look to the right, at the ones, if it is 5 or more than round or change the tens by + 1 if not, the number remains as is, followed by zeros.

129 is estimated to 130, since 9 is greater than 5 and 2 goes up by 1.