Age 6+

10 minutes



Collect the sum
Remove the red numbers
Game Description

In Brief

Learning objective

In Sum, the players will be trained in basic mental arithmetic having to add numbers that make up a specific sum (no higher than 30). To achieve the highest score possible, the players will need to keep their cool and play strategically.

Game objective

In Sum, the aim is to collect a specific sum in each of the four different levels (5, 10, 20 or 30). When collecting the sum, the players should also try to include as many of the red numbers as possible that will keep appearing on the playing board.

Detailed Description


The game begins with the playing board being covered in white octagons containing single-digit numbers. To score points, the players need to drag a finger over numbers that will add up to the chosen sum. Each time the players correctly manage to collect the chosen sum, the selected numbers are replaced by new numbers and the players are awarded points. In the course of the game, more and more of the numbers will automatically turn red. Moreover, every arithmetical error the players make will result in more red numbers. Since the game ends when every number on the playing board has turned red, the players will not only need to concentrate on collecting correct sums, they will also need to focus on removing red numbers.

How to remove red numbers

To remove red numbers, the players have to start counting on a white number, and then keep counting through the red number(s). If the players get to a correct sum, all the selected numbers – including the red – will disappear from the playing board and be replaced by new white numbers. During the game, the players will also get the chance to collect fire extinguishers which can be used for removing red numbers.

Collecting and using fire extinguishers

Some of the octagons on the playing board will not contain numbers, but fire extinguishers. Since these octagons do not contain a number, their value is always 0. By including one or more octagon containing a fire extinguisher in a correct sum, the players collect these fire extinguishers which they can use later in the game for removing red numbers. Collected fire extinguishers will appear at the bottom of the screen. To use a fire extinguisher, the players simply need to select it from the area with collected fire extinguishers and drag it to an area on the playing board. When a player has dragged the fire extinguisher to the designated area, they simply need to lift the finger from the touchscreen, and the fire extinguisher will be activated and remove all red numbers in that area.

Point system

For each correct calculation, the players will receive points. The number of points corresponds to the sum that they collect. For example, if the players need to collect a sum of 30, they receive 30 points for each time they successfully do so. The current high score of each difficulty level that the players can choose from is displayed in the main menu of the game. This gives the players a target to try and beat.

Detailed Description


The players have four different levels to choose from.

Sum 5

This is the easiest of the four levels. At this level, all the numbers on the playing board are ones, and the sum that the players need to collect is 5.

Sum 10

At this level, the numbers on the playing board vary between 1-3 and the sum that players need to collect is 10.

Sum 20

At this level, the numbers on the playing board vary between 2-6 and the sum that players need to collect is 20.

Sum 30

This is the most difficult level. At this level, the numbers on the playing board vary between 3-8 and the sum that players need to collect is 30.