Which doubles are actually worth memorizing?

The ones from one plus one up to twelve plus twelve, which is about twelve facts and takes far less time than it sounds. They pay for themselves because so many other sums sit one step from a double, and because doubling reappears in multiplication, halving, and mental arithmetic with larger numbers. This game covers exactly that range.

What is the near-doubles strategy?

It is solving a sum whose two numbers are one apart by using the double next door. For six plus seven, a child recalls six plus six is twelve and adds one to get thirteen. It only works when the doubles themselves come back instantly, which is why the doubles get drilled first and the strategy is taught immediately afterwards.

Is answering fast the point, or is that just pressure?

Speed here is evidence rather than a goal. A child who answers a double quickly has it in memory, and that frees attention for the harder parts of a longer problem. If the answers are slow but correct, nothing is wrong and the facts are still settling, so keep the sessions short and stop before the rushing starts.

← All games

Doubles Dash

Double the number, fast.

Grades 1-2 · Doubles facts, the backbone of mental addition

How to play

1A double appears, like 7 + 7.
2Tap the total.
3Doubles are worth knowing cold, because near-doubles come free from them.
4Grow your streak.

Try a few

7 + 7
Answer: 14
Seven and seven is fourteen, and the reason to know it instantly is what it unlocks rather than the fact itself. Once fourteen is automatic, seven plus eight needs no counting at all: eight is one more than seven, so the answer is one more than fourteen, which is fifteen. Six plus seven comes out of the same fact from the other side, one less than fourteen, so thirteen. One memorized double is quietly paying for three sums.
9 + 9
Answer: 18
If nine plus nine is not yet known by heart, build it from ten rather than by counting. Ten and ten is twenty, and each nine is one short of a ten, so the total is two short of twenty, which is eighteen. That is a better route than starting at nine and counting nine more, because it uses a fact your child already owns and only asks for one small adjustment. The same trick gives eight plus eight as twenty take away four, which is sixteen.
12 + 12
Answer: 24
This is the largest double the game asks for, and it is the one where children stop counting and start using structure. Split each twelve into ten and two. The two tens make twenty, the two twos make four, and twenty and four is twenty-four. Doubling by splitting into tens and ones is the method that keeps working long after the counting runs out, which is why doubling twelve is worth more practice than doubling three.

Why this game helps

Doubles are the small set of addition facts most worth knowing instantly, because so much else is one step away from them. A child who knows 7 + 7 = 14 can get 7 + 8 without counting, by seeing it as one more than the double, and the same trick covers 6 + 7 and 8 + 9 and dozens of others. That is the near-doubles strategy, and it only works if the doubles themselves are automatic. Drilling the twelve or so doubles is a genuinely high-return use of five minutes, which is not true of most fact practice.

If your child finds this hard

The wrong answer that turns up most often here sits one away from the right one, so seven plus seven comes back as thirteen or fifteen. It is the recorded off-by-one on a double, and it comes from counting the second seven on fingers while the first is still being held in mind. The choices in this game are drawn close to the answer, so a near miss like thirteen may well be sitting on screen and look perfectly reasonable. Doubles are not meant to be counted, so if fingers appear, that fact is not known yet and should be built from a nearby one.

A smaller group of children answer eight to seven plus seven, or three to two plus two. They have added one rather than doubled, usually because the instruction to double got lost and two numbers on a screen seemed to want something small done to them. Say the problem as a picture instead of a sum: seven marbles in this hand, seven in the other, how many altogether. Two equal groups is what a double means, and a child who can see the two groups does not answer eight.

If the small doubles are solid and the big ones are not, do not drill the whole list again. Build the missing ones from the ones already owned. Six plus six is twelve, so seven plus seven is twelve plus two, which is fourteen. Ten plus ten is twenty, so nine plus nine is two less. Working from a known double to its neighbour is the same reasoning the near-doubles strategy needs later, so the repair and the goal are the same activity.

Common questions

Which doubles are actually worth memorizing?: The ones from one plus one up to twelve plus twelve, which is about twelve facts and takes far less time than it sounds. They pay for themselves because so many other sums sit one step from a double, and because doubling reappears in multiplication, halving, and mental arithmetic with larger numbers. This game covers exactly that range.
What is the near-doubles strategy?: It is solving a sum whose two numbers are one apart by using the double next door. For six plus seven, a child recalls six plus six is twelve and adds one to get thirteen. It only works when the doubles themselves come back instantly, which is why the doubles get drilled first and the strategy is taught immediately afterwards.
Is answering fast the point, or is that just pressure?: Speed here is evidence rather than a goal. A child who answers a double quickly has it in memory, and that frees attention for the harder parts of a longer problem. If the answers are slow but correct, nothing is wrong and the facts are still settling, so keep the sessions short and stop before the rushing starts.

Try these next

Free games are a great warm-up. For a full program that finds exactly where your child gets stuck, Nova Academy is a personal math tutor powered by AI for grades 1 to 5.

Start a free trial →