A Challenge For You
Now for those of you who like a good maths problem or two, or have too much time on your hands, or who are trying to avoid something you don't want to do, I need your help.
I cannot figure out this question.
Your mission: what is the answer? How did you get it? You have until Friday morning 7.30am to tell me what you think.
The numbers A and B each have three digits. Robin was asked to calculate A x B. Instead he put A on the left of B to form a six-digit number D. His answer was three times the correct answer. Find A and B.
Help!
posted by Liz, Scott and Harry @ 9:57 pm
1 Comments:
Ok, I'm a bit of a geek, and can't refuse a problem...
A = 167, B = 334.
The way that ultimately gave me a solution may or may not be useful for your purposes. There is probably a far more elegant way of doing this. Blame it on the fact I haven't done maths in ages. Here it is:
The information we have is:
(1) A x 1000 + B = 3 x A x B
(2) 99 < A,B < 1000
(3) A,B are real numbers
Rearrange (1):
(1a) A = B / (3B - 1000)
(1b) B = 1000A / (3A - 1)
Put lowest and highest values of A from (2) into formula (1b):
A = 100, B = 334.44 (2dp), A = 999, B = 333.44 (2dp).
Check out something in the middle (to check it's one to one)
A = 500, B = 333.56 (2dp)
So, from the looks of things, B has to be between 334.44 and 333.44. According to (3), this means:
B = 334
On the basis of 1a:
A= 167
Yeah... I'm a geek
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