Tuesday, September 27, 2011

Problem Solving Heuristics Question 2 (Mason Sim (16) , Shaun Ng(17) )

Q2. The tens digit of a two-digit number is 5 more than the units digit. The number formed by reversing the digits is 128 less than twice the original number. Find the Original .

We found that whenever we subtracted the reversed number from the original number, we always got 45.

Solving it.
Original Number = x
Reversed Number = y

So from our pattern, we found out that x-y = 45
From the question, we know 2x-y = 128
There is a similarity between the both equations, so we can swap the numbers.
Therefore, 2x- y = 128 is the same as x+45 = 128
We move the numbers to the other side of the bracket and end up with
x= 128-45
To check, the first digit has to be 5 more than the second digit which is correct.
Therefore our answer is 83

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