Prime numbers are numbers that are only divisible by themselves and 1. For example, 3 is a prime number, but 4 isn't (because 4 is divisible by 2). You can think of prime numbers as very small families: they only ever have two people in them! Only themselves and 1. You can't fit any other numbers into them with nothing left over. 5 is one of these lonely numbers (only 5 × 1 = 5), but you can see that 6 has 2 and 3 in its family as well (6 × 1 = 6, 2 × 3 = 6). So 6 is not a prime number. Use the arrow keys to navigate around the board and to avoid the Troggles. Press the spacebar to eat a number.
’S e àireamhan a th’ anns na prìomh-àireamhan nach gabh roinneadh ach leotha fhèin no le 1. Mar eisimpleir, tha 3 na prìomh-àireamh ach chan eil 4 (oir gabhaidh 4 roinneadh le 2). ’S urrainn dhut beachdachadh air prìomh-àireamhan mar theaghlaichean glè bheaga: chan eil ach dithis bhall aca! ’S e seo an àireamh fhèin agus 1. Chan urrainn dhut àireamh sam bith eile a chur annta gun dad air fhàgail. Is 5 aon dhe na h-àireamhan aonarach seo (chan e ach 5 x 1 = 5), ach chì thu le 6 gu bheil 2 is 3 san teaghlach aice-se cuideachd (6 x 1 = 6, 2 x 3 = 6). Mar sin, chan e 6 na prìomh-àireamh. Cleachd na saighdean gus gluasad timcheall a’ bhùird is na bòcain a sheachnadh. Brùth air a’ spacebar gus àireamh ithe.