It's a classic game adapted on the DS (plus or minus in english, plus ou moins in french)
The DS will think to a number between 40 and 70.
You will have to find it.
Choose a number (always between 40 and 70 of course) and press A.
The DS will say to you Plus if the number is higher than the one you choose.
The DS will say to you Minus if the number is lower than the one you choose.
The game continues like that until you find the good number.
Download
Source- neoflash