1. ## help help please

when two digit number KY is multiplied by itself, the result is the 3 digit number ZLK i.e(KY) x(KY) = ZLK. The number that K stands for is
a)1 or 9
b)2 or 6
c)3
d)1

2. Originally Posted by kl050196
when two digit number KY is multiplied by itself, the result is the 3 digit number ZLK i.e(KY) x(KY) = ZLK. The number that K stands for is
a)1 or 9
b)2 or 6
c)3
d)1
The statement of the problem implies that "Y" does not matter. What is 19*19. Is it a 3 digit number? What about 99*99, 29*29, etc.?

Since you are squaring, another way to do this is to look at $\sqrt{1000}$. What does that tell you?

3. Hello, kl050196!

We can solve this by Elimination.

When a 2-digit number $KY$ is squared,
the result is the 3-digit number $ZLK$ . . . i.e $(KY)^2 \:=\: ZLK$
The number that $K$ stands for is:

. . $(a)\;1\text{ or }9 \qquad (b)\;2\text{ or }6 \qquad (c)\;3 \qquad (d)\;1$
The answer cannot be (a) since $(9Y)^2 \,\geq \,8100$

The answer cannot be (b) because a square cannot end in 2.

The answer cannot be (c) because a square cannot end in 3.

Therefore . . .