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Contributor: Ashley Nail Murphy. Lesson ID: 14103
Ready to use a math magic trick? Learn about double facts and how they magically make you a master at mental math. Use double facts to add quickly and solve problems!
Marty the Magician needs to solve a math problem!
8 + 9 = ____
He could count on his fingers, but Marty does not have enough fingers for that math!
He could draw a picture, but Marty would spend a long time drawing. He needs an answer fast!
He could use a number line, but Marty needs an answer really fast!
A magic trick! After all, Marty is a magician!
He can use doubles facts magic!
Doubles facts are when you add the same number to itself.
For example, look at two pencils.
Now, double the pencils. Double means to make another set with the same amount of things.
Make an addition sentence.
2 + 2 = 4
There are 4 pencils! You just used doubles facts!
Now, look at these ice cream cones. Find the total number of scoops.
3 + 3 = 6
There are 6 total ice cream scoops!
Both ice cream cones have 3 scoops. You doubled the scoops to find the total!
You can use doubles facts to help find other sums, too.
Look at these ice cream cones.
You know this doubles fact: 3 + 3 = 6.
One cone has 1 more scoop than before. So, 3 + 4 must be one more than 6. That’s 7!
3 + 4 = 7
Here is another example!
You know this doubles fact: 3 + 3 = 6.
A cone has one less scoop. So, 3 + 2 must be one less than 6. That's 5!
3 + 2 = 5
Study more doubles facts!
Click the NEXT button and visit the Got It? section to practice doubles facts!
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