What is the tens digit of positive intiger r?
1. The tens digit of r/10= 3
2. The hundreds digit of 10r = 6
OA B
1. The tens digit of r/10= 3
2. The hundreds digit of 10r = 6
OA B
I solved it this way -
assume r = 100x + 10y + z ....equation 1
The question is asking is you can find y.
From hint 1 & eqn. 1,
r/10 = 10x + y +(maybe some fraction). All the hint gives you here is the ten's place of r/10 which gives you x, not y.
From hint 2 & eqn.1,
10r = 1000x + 100y + 10z. -- which can otherwise be written as the number xyz0. The hint gives you the hundred's place of 10r , which happens to be y, which is what you want.
So, the answer is B.
I should admit that I couldn't crack it in under 2 minutes, but now I discovered how I can, for the next time!
