It's when you switch the order of the numbers you are adding. The answer, or sum, stays the same. For example, \(2+6\) and \(6+2\) are turn-around facts.
$$ 3 + 5 = 8 $$ What is the turn-around fact?
$$ 5 + 3 = 8 $$
If you know \(7 + 2 = 9\), what other addition fact do you know for free?
You also know that \(2 + 7 = 9\).
Does the order matter when you add numbers?
No, the order does not matter in addition. You get the same sum either way.
Solve: \(4 + 6 = ?\) and \(6 + 4 = ?\)
Both equal \(10\). \(4 + 6 = 10\) and \(6 + 4 = 10\).
This math rule is called the Commutative Property of Addition. Can you use it to solve \(1+8\) if you know \(8+1=9\)?
Yes. Since \(8+1=9\), then \(1+8\) must also equal \(9\).
$$ 9 + 3 = ? $$
$$ 9 + 3 = 12 $$
Using the turn-around rule, what is \(3+9\)?
$$ 3 + 9 = 12 $$
Why are turn-around facts helpful?
They reduce the number of addition facts you have to memorize. If you know one, you automatically know its partner!
