Itimaal
![](http://upload.wikimedia.org/wikipedia/commons/thumb/a/a5/6sided_dice.jpg/511px-6sided_dice.jpg)
Ku-tiirsaneyaasha ururka {a.b.c} waxaad u ratibi kartaa lix siyaabood oo kala duwan:
abc | bac | cab |
acb | bca | cba |
Rattibaad kasta waxay kaga duwantahay tan kale horsiimada ku-tiirsanayaasha.
Raabaqaad waa rattibaad kasta oo ku-tiirsaneyaasha urur la siinayo horsiimo huban.
Abnaqanka n oo loo qoro n! waa taranka tirsiimada laga bilaabo 1 ilaa n taasoo ah:
n! = 1.2.3.4.... (n----3) (n----2) (n----1) n.
Matalan 5! = 1.2.3.4.5. = 120
Ogoow 0! = 1, sidoo kale 1! = 1
Sumadda waxay u taagantahay raabaqaad n shey oo markiiba la qaato r shey sida, waa tirada raabaqaad 8 shey oo markiiba la qaat qaatay 3 shey.
Tirada raabaqaad n shey oo kala duwan oo markiiba r shey la israacsho waxay la mid tahay
- n (n -- 1) (n -- 2) . . . (n-- r + 1)
= :
Haddii r = n
= = (n -- 2) (n -- 2) .... 3.2.1 = n!
Tusaale
b) : = 5; : = 5.4 = 20; : = 5.4.3 = 60
- = 5.4.3.2 = 120
- = 5.4.3.2.1 = 120
t) Tirada siyaalaha afar qof ay ugu fariisan karaan 6 kursi waa
- = 6.5.4.3 = 360
j) Imisa siyaabood ayaa loo safi karaa shan buug oo kala duwan? taasi waxay ka dhigantahay tirada raabaqaadka shan buug oo la qaato markiiba 5, ama : waa imisa?
- = 5! = 5.4.3.2.1 = 120