Doubles facts are addition facts where both numbers are the same, like 4 + 4 = 8 or 7 + 7 = 14. There are ten of them from 1 + 1 to 10 + 10, and every answer is an even number. Once kids know them, they can use them to work out near doubles such as 6 + 7.
A doubles fact adds a number to itself. "Double 6" means 6 + 6, which is 12. Doubles are easy to picture because the two parts match: two hands, two rows of eggs, two sides of a bug.
They are also a popular place to start fact practice. A What Works Clearinghouse (WWC) practice guide on helping elementary students who struggle with math suggests that when working on addition facts, you might start with adding 1 or with doubles, and then move on to harder combinations.
Here are all ten, each with a real-world picture to help it stick:
1 + 1 = 2: two eyes
2 + 2 = 4: four wheels on a car
3 + 3 = 6: six legs on an insect, three on each side
4 + 4 = 8: eight legs on a spider, four on each side
5 + 5 = 10: ten fingers on two hands
6 + 6 = 12: a dozen eggs in two rows of six
7 + 7 = 14: two weeks is 14 days
8 + 8 = 16: two spiders have 16 legs
9 + 9 = 18: an 18-wheeler truck, nine wheels on each side
10 + 10 = 20: ten fingers and ten toes
Bonus: 0 + 0 = 0 is a double too, and some kids love that one.
They unlock near doubles. The Common Core first grade standards list "creating equivalent but easier or known sums" as an addition strategy, with the example of adding 6 + 7 by thinking 6 + 6 + 1 = 12 + 1 = 13.
They connect to even numbers. In second grade, children are expected to tell whether a group of up to 20 objects is odd or even, and to write an even number as a sum of two equal addends, such as 12 = 6 + 6.
They help with subtraction. If 8 + 8 = 16, then 16 - 8 = 8. The first grade standards name using the relationship between addition and subtraction as a strategy.
They lead to halving. Knowing that double 7 is 14 means half of 14 is 7, which comes up whenever you share things equally.
They support fluency goals. The Common Core expects second graders to add and subtract within 20 fluently using mental strategies, and to know all sums of two one-digit numbers from memory by the end of the year.
Near doubles are facts where the two numbers are close, like 7 + 8. Kids find a double they know and adjust.
Doubles plus one: 6 + 7 is double 6 plus one more, so 12 + 1 = 13.
Doubles minus one: 6 + 7 is also double 7 minus one, so 14 - 1 = 13.
Doubles plus two: 6 + 8 is double 6 plus two, so 12 + 2 = 14. It's also the same as double 7.
Practice by pairing them. Say "5 + 5," then "5 + 6." Say "8 + 8," then "8 + 9." Ask your child how the first answer helps with the second. The WWC guide gives the same example: reminding students of the "double plus one" strategy can help them solve 6 + 7 if they don't know it automatically.
Build them with objects. Make two equal rows of blocks or coins. Count them all, then say the fact: "4 and 4 make 8."
Use a mirror. Stand three toy cars in front of a small mirror. How many cars do you see now? Try other numbers.
Use fingers. Hold up the same number of fingers on each hand. Fingers make doubles up to 5 + 5 easy to see.
Say them in order, then mixed. Go from 1 + 1 to 10 + 10, then ask them out of order.
Mix in facts your child already knows. The WWC guide suggests including easier facts as you move to harder ones, so kids practice telling fact types apart.
Add near doubles. Once doubles feel easy, pair each double with its plus-one neighbor.
For where doubles fit in the bigger picture, see our step-by-step guide on how to teach addition.
Doubles war. Take the face cards out of a deck. Each player flips one card and doubles it. The bigger double wins both cards. Aces count as 1.
Roll and double. Roll one die, say the double, and collect that many beans. The first player to reach 30 beans wins.
Doubles memory. Make cards with a fact on one card (7 + 7) and its answer on another (14). Lay them face down and play a matching game.
Clap and echo. Clap 4 times. Your child echoes with 4 claps. How many claps altogether?
Near-double detective. Call out a fact like 8 + 9. Your child names the double that helps ("8 + 8!") before giving the answer.
Doubles bingo. Draw grids with even numbers from 2 to 20. Call out doubles facts, and players cover the answers.
A simple rhythm can help facts stick. Try marching while you chant: "Double one is two, double two is four, double three is six, now let's do some more!" Keep going up to double ten. You can also play call and answer: you say "Double seven!" and your child answers "Fourteen!" Speed up only if your child is enjoying it.
Keep practice short and upbeat. The WWC guide describes timed fact activities as brief, usually 1 to 5 minutes, and notes that some children feel anxious during them. Its advice: avoid handing over a big page of problems, use flashcards or activities that show only a few problems at a time, and let a group try to beat its own earlier score instead of competing alone. At home, that can mean racing your family's own best score together.
1 + 1 = 2, 2 + 2 = 4, 3 + 3 = 6, 4 + 4 = 8, 5 + 5 = 10, 6 + 6 = 12, 7 + 7 = 14, 8 + 8 = 16, 9 + 9 = 18 and 10 + 10 = 20.
A fact where the two numbers are one apart, like 5 + 6. Use the double you know (5 + 5 = 10) and add one more to get 11.
The Common Core doesn't list doubles as a separate standard, but its first grade standards use a near-doubles example, and its second grade standards expect children to know all sums of two one-digit numbers from memory by the end of the year.
Link each one to a picture, practice a few minutes at a time with games, and mix in facts your child already knows. Once doubles come quickly, move on to near doubles.
Number Beasts: Bond Lab is a puzzle game about making exactly 10 rather than doubles, so it pairs best with the make-10 side of fact practice, where 5 + 5 is the one double that lands on 10. You launch a number at a beast and it pops when the total is exactly 10, and if you overshoot, the leftover number keeps flying to the next beast. It is free for iPhone and iPad with no ads, no accounts and no in-app purchases, and it works offline.
Get Number Beasts free on the App Store
Common Core State Standards: Grade 1, Operations and Algebraic Thinking
Common Core State Standards: Grade 2, Operations and Algebraic Thinking