Comments on: Numbers – The Three Spartans

By: yo

yo — Tue, 10 Nov 2009 02:22:09 +0000

wad is the meaning of lowest common multiple

By: Li-sa

Li-sa — Thu, 26 Jun 2008 04:31:20 +0000

当我是交流生吧，反正香港会考生学的数学和新加坡的差不多，只是没有集合(set)和自然对数(natural logarithm)。但这无所谓，因为我会自动自觉地学习。
不过我住在香港多年才称自己「香港人」。

By: Li-sa

Li-sa — Wed, 25 Jun 2008 06:51:46 +0000

我係香港人，也是會考生。瞧我的繁體中文！

By: Miss Loi

Miss Loi — Tue, 24 Jun 2008 16:48:30 +0000

When you see stuffs happening simultaneously "every x seconds/minutes etc" (being traffic lights flashing, water fountains sprouting, buses arriving, Spartans signaling etc.) in the question and you're being asked to find when they will happen at the same time, you should instantly recognize that you're dealing with LCM!

Another way of looking at and understanding this question for those who may still be unsure:

1st Spartan signals at: 16s, 32s, 48s, 64s, ... multiples of 16
2nd Spartan signals at: 40s, 80s, 120s, 160s, ... multiples of 40
3rd Spartan signals at: 64s, 128s, ... multiples of 64

So the time when all three signals at the same time is the Least Common Multiple of 16, 40 and 64, with detailed workings kindly provided courtesy of fggffggf above

P.S. fggffggf 你係廣東人?

By: fggffggf

fggffggf — Wed, 18 Jun 2008 07:48:38 +0000

That means I'm going to find the LCM of the 16, 40 and 64, then applying the finding to the actual question.

.'. The LCM is .
320 seconds = 5 minutes and 20 seconds
.'. The time, correct to the nearest minute, when the three Spartan scouts signal simultaneously is 0605 hours.

And putting Math aside, the Spartans movie 笑到我辘地！