Rounding to the Nearest Ten

Rounding helps us find a number that is simpler to use but still close to the exact amount. When we round to the nearest ten, we are looking for the "ten" (like $10, 20, 30, 40$, etc.) that is closest to our number.

The Rule for Rounding

To round a number to the nearest ten, you only need to look at the ones digit (the number on the far right).

1. Look at the ones digit.
2. If the ones digit is $0, 1, 2, 3,$ or $4$, you round down. Keep the tens digit exactly the same and change the ones digit to $0$.
3. If the ones digit is $5, 6, 7, 8,$ or $9$, you round up. Add $1$ to the tens digit and change the ones digit to $0$.

A helpful rhyme to remember: "Four or less, let it rest. Five or more, let it soar!"

Example Problems

Round $67$ to the nearest ten

• The tens digit is $6$ and the ones digit is $7$.
• Because the ones digit is $7$ (which is $5$ or more), we round up.
• The $6$ becomes a $7$, and the ones digit becomes $0$.
• Answer: $70$

Round $145$ to the nearest ten

• Even though this is a three-digit number, the rule is the same! Look at the tens ($4$) and the ones ($5$).
• Because the ones digit is $5$, we round up.
• The tens digit $4$ becomes a $5$, and the ones digit becomes $0$. The hundreds digit stays exactly the same.
• Answer: $150$

Is $35$ closer to $30$ or $40$?

• The number $35$ is right in the middle of $30$ and $40$.
• However, in math, our special rule says that if a number ends in exactly $5$, we always round up.
• Answer: It rounds to $40$.