1) Let the digits be x and y and the number be xy.
Reversed number = yx.
Magnitude of the number = 10x + y
Magnitude of reversed number = 10y + x
Given:
y - x = 1
(10x+y)/(10y+x) = 5/6.
=> 6(10x+y) = 5(10y+x)
=> 60x + 6y = 50y + 5x
=> 55x = 44y
We have y - x = 1 => y = x + 1
=> 55x = 44(x+1)
=> 55x = 44x + 44
=> 11x = 44
=> x = 4, y =5
2) Here we are told that the 100's digit is 4 times the 1's digit.
Therefore our only options are (1,4) and (2,8) for (1's digit, 100's digit).
Case(1):
The number is 4X1.
Sum of digits is 14 => Missing digit is 14 - 4 - 1 = 9.
The number is 491.
The difference between this and the reversed number is (491-194)=297. => this case is invalid.
Case(2):
The number is 8X2.
Missing digit = 14 - 8 - 2 = 4.
The number is 842.
Number - reversed number = 842 - 248 = 594.
Therefore, the correct answer is 842.
2007-06-18 06:00:05
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answer #1
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answered by Anonymous
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(1) To solve, I just multiplied 5/6 by whole numbers until I got the answer. You will find it is 45 and 54.
(2) We know that the hundreds digit is either 4 or 8 from the first statement. Likewise, the units digit is 1 or 2. All three add to 14. Let's write our possibilities:
4x1 ==> 4 + x + 1 = 14 ==> x = 9
==> 491
8y2 ==> 8 + y + 2 = 14 ==> y = 4
==>842
Reverse both and subtract:
491 - 194 = 297 ==> not it
842 - 248 = 594 ==> Correct.
2007-06-18 12:58:59
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answer #2
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answered by yeeeehaw 5
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It would be cheating to give you the answer (see other answers if you want to cheat), but here's a start:
For the first question: Use variable "a" to stand for one digit; and variable "b" to stand for the other digit. Then:
"a number of two digits" is: 10a + b. (Do you see why? Try an example. if a=5 and b=3, then "a number of two digits" is 10*5 + 3, or 53. It works for any two digits.)
"the number with the digits reversed" is: 10b + a.
"the difference of the digits" is: a&endash;b (or possibly: b&endash;a. It depends on which is bigger, a or b, which you should be able to figure out.
Now you've got some equations, so you can just use the algebra you already know.
For the second problem: Similar thing, but now use a, b and c.
"a number of three digits": 100a + 10b + c
"the hundred digit": a
"the unit digit" c
etc.
2007-06-18 13:01:52
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answer #3
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answered by RickB 7
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If the tens digit is x, the units digit is (x+1). The value of the number is 10x + x +1 = 11x + 1. Reversed, it's worth 10(x+1) + x = 11x + 10. We know the reversed number is greater than the original since their quotient is less than 1
So (11x + 1)/(11x + 10) = 5/6
Cross multiply to get 55x + 50= 66x + 6
Thst's 11x = 44 so x=4 and the other digit is 5
so the number is 45
2007-06-18 13:00:15
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answer #4
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answered by hayharbr 7
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The first solution is 45.
45 and 54 are both multiples of nine.
45/9 = 5
54/9 = 6
Therefore, 45/54 = 5/6.
Also, the difference between the digits (5 and 4) is equal to one.
The second answer is 842.
8/2 = 4 - This fulfills the first criteria (100s digit is 4x the units digit).
8+4+2 = 14
If you reverse the digits, you get 248. 842-248=594.
God, I love math.
2007-06-18 13:02:49
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answer #5
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answered by Anonymous
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45 / 54 and 842
2007-06-18 12:58:50
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answer #6
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answered by bilbo 3
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let the nos. be x and x+1
atp,
[10*x+(x+1)]/[(x+1)*10+x]=5/6
simplifying we get , x=4 and x+1=5
number is 45
2007-06-18 13:23:24
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answer #7
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answered by goswamisayan 1
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