K is a two digits number, if the sum of the tens' and units'

Question

. K is a two digits number, if the sum of the tens' and units' digit is 3 less than the product of each digit. What is the value of K?

Hi guys any ideas on how to tackle this problem?

agsfaltex · Answer

x+y = xy - 3

xy - y = 3 + x

y(x-1) = (3+x)

y = (3+x)/(x-1)

If we plug in X = 1 through 9 we get intergers for Y for the following two digit numbers:

25
33
52

apollo168 · Answer

Thanks for the help

haas_mba07 · Answer

Agree with above answer...
question needs to be refined..

If K = 10x+y, then
K = {25,52, 33}

BTW for any problem which refers to a two digit problem, use the K = 10x+y way of representing the digits .. Makes it easier..
Then again, you might already know that :-)

apollo168 · Answer

Hi,

Thanks for the tip. But in this case how do you utilize the 10x+y thingie?

haas_mba07 · Answer

Yes, for this problem it doesn't help.. but in general there are problems which ask you to flip the digits and find the possible sums.

For ex. if the digits of a two digit number are flipped and the two numbers added, which of the following is a possible sum.. 
So K= 10x+y, K'=10y+x,
K+K' = 11(x+y)...
Sum has to be a multiple of 11, 

Same way with difference .. K-K' = 9(x-y)
If (x+y) or (x-y) is given you can find the difference or sum.

Again, you might already know this.

apollo168 · Answer

Ah yeah that's right. Ive encountered a few of those types of problems

THanks

K is a two digits number, if the sum of the tens' and units'

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