Addition fact · doubles
10 + 10 = 20
Ten plus ten equals twenty. 10 + 10 is a double: the same number twice. Doubles are worth knowing by heart, because so many other facts lean on them.
See 10 + 10
10 red and 10 yellow. The first frame fills up at 10, and 10 more sit in the next one.
It's a double
- See two equal groups of 10.
- Fingers and toes: 10 of each, 20 in all.
- So 10 + 10 = 20. Say it a few times until it comes without counting.
Its fact family has two facts
10, 10 and 20 go together, so learning one of these helps with all of them. See the family.
Practice 10 + 10 in a game
A fact sticks when a child has to pull it from memory again and again. In this game 10 + 10 keeps coming back between the other facts in its family.
Every round leans on 10 + 10
Free to play · no signup · works on phones, tablets and computers
Quick quiz
10 + 10 FAQ
What is 10 + 10?
10 + 10 = 20. In words: ten plus ten equals twenty.
Why is 10 + 10 called a double?
Because both numbers are the same. It has a smaller fact family than most: just 10 + 10 = 20 and 20 − 10 = 10.
What grade learns 10 + 10?
This is a first and second grade fact. Common Core has children add within 20 in first grade (1.OA.C.6), and by the end of second grade know all sums of two one-digit numbers from memory (2.OA.B.2).
Is Sumtown really free?
Yes. The whole game plays free in your browser, with no signup, no ads and no time limit. All fourteen mini games are in it. An iPhone app is on its way, and you can read what it will add.
An app is on its way
We're building a Sumtown app for iPhone with the parts that need a real app: offline play for car rides, a town map that remembers how far your child got, and a parent report on every fact. Until then, the whole game is free right here.
Coming soon on theApp Store