Estimation is finding a number that is close to the exact answer. It's like making a smart guess to get an "about" answer quickly.
Why is it useful to estimate answers?
Estimation helps you check if your final answer is reasonable and allows you to calculate numbers quickly in your head, especially in real-life situations like shopping.
Words like "about," "close to," and "approximately" are clues that you should do what?
These words are clues that you should estimate the answer instead of finding the exact one.
When rounding to the nearest ten, what digit do you look at?
You look at the digit in the ones place.
What is the rule for rounding if the ones digit is \(5\) or more (\(5, 6, 7, 8, 9\))?
You round up to the next higher ten. For example, \(27\) rounds up to \(30\).
What is the rule for rounding if the ones digit is \(4\) or less (\(4, 3, 2, 1, 0\))?
You round down. This means the tens digit stays the same, and the ones digit becomes \(0\). For example, \(23\) rounds down to \(20\).
Round the number \(48\) to the nearest ten.
The ones digit is \(8\), which is \(5\) or more, so you round up. \(48\) rounds to \(50\).
Round the number \(62\) to the nearest ten.
The ones digit is \(2\), which is \(4\) or less, so you round down. \(62\) rounds to \(60\).
Round the number \(85\) to the nearest ten.
The ones digit is \(5\), so you round up. \(85\) rounds to \(90\).
What are the two tens that the number \(34\) is between?
It is between \(30\) and \(40\).
Is \(34\) closer to \(30\) or \(40\)?
It is closer to \(30\). That's why it rounds down to \(30\).
Round the number \(19\) to the nearest ten.
The ones digit is \(9\), which is \(5\) or more, so you round up. \(19\) rounds to \(20\).
Round the number \(91\) to the nearest ten.
The ones digit is \(1\), which is \(4\) or less, so you round down. \(91\) rounds to \(90\).
