Rounding is making a number “prettier”. In cases where we are allowed to, the reason to round a number is to make it easier to do arithmetic with. Which number you should round off to depends on the practical situation you are in.
Rule
Rules for Rounding
You round the number down if the number in the place you are rounding to is followed by
You round the number up if the number in the place you are rounding to is followed by
Think About This
, , , and are closer to the number you get when you round down. , , , and are closer to the number you get when you round up.
Example 1
Round 43 to the nearest ten.
Because you’re rounding to the nearest ten, you have to look at the number in the position to the right of the tens place. That’s the ones place. From the rule above, you know that is rounded down, which gives you
The symbol “” means “approximately equal to”, and is used when two numbers are almost the same.
Example 2
Round to the nearest ten.
Because you’re rounding to the nearest ten, you have to look at the number in the position to the right of the tens place, which is the ones place. From the rule above, you know that is rounded up, which gives you
Example 3
Round to the nearest ten.
Because you’re rounding to the nearest ten, you have to look at the number in the position to the right of the tens place, which is the ones place. From the rule above, you know that is rounded down, which gives you
Example 4
Round to the nearest one.
Because you’re rounding to the nearest one, you have to look at the number in the position to the right of the ones place, which is the tenths place. From the rule above, you know that is rounded down, and that gives you
Example 5
Round to the nearest one.
Because you’re rounding to the nearest one, you have to look at the number in the position to the right of the ones place, which is the tenths place. From the rule above, you know that is rounded up, which gives you
Example 6
Round 2385 to the nearest hundred.
Because you’re rounding to the nearest hundred, you have to look at the number in the position to the right of the hundreds place, which is the tens place. From the rule above, you know that is rounded up, which gives you
Math Vault
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