# Still Okay With Your Maths?

Dear students / readers,

After having a long school break, why don’t you try this maths brain teaser 🙂

**Football matches are to be organized in a round-robin format (each participating team plays a match against every other team only once). If 21 matches are totally played, how many teams participated?**

*Dalam satu pertandingan bola sepak yang diadakan secara round-robin (satu pasukan perlu melawan setiap pasukan lain hanya sekali sahaja). Jika 21 jumlah perlawanan telah diadakan dalam pertandingan ini, berapakah jumlah pasukan yang mengambil bahagian*?

Is anyone interested to try? The calculation is simple, but it really needs logical thinking 🙂

Posted on January 12, 2010, in Info Matematik. Bookmark the permalink. 7 Comments.

i think its 7!

Hi teacher! After calculating, i can get the answer, there is 7 teams playing. It’s all menatal and logic =P

Ya, true. The answer is 7 🙂 . Quite easy ya?

Yeah…^^

how to get 7??? got 3 only….

Dear lin,

If 7 teams participated, the first team plays matches against the other 6 teams. The second team has already played against the first team, so that second team has to play matches against only the other 5 teams. In this manner, the second-last team has to play against only one team, and the last team has already played against all the teams. Therefore, the total number of matches is 6+5+4+3+2+1+0 = 21 matches 🙂

oh ok..hehe