† and ¥ represent nonzero digits, and (†¥)² - (¥†)² is a perfect square. What is that perfect square?
Choose one:
A) 121 B) 361 C) 576 D) 961 E) 1089
If AB is a 2 digit number such that A is the tens digit and B is the units digit, the place value of A is 10 and place value of B is 1.   So AB = 10A + B   Say, AB = 15   A = 1   B = 5   Is AB = A + B? No. 15 is not equal to   1 + 5= 
<gadget id="calculator">  1 + 5</gadget>
<output>6</output>
6   AB= 10A + B = 10*1 + 5= 
<gadget id="calculator">10*1 + 5</gadget>
<output>15</output>
15   When you square AB, what will you get?   Is it (A + B)^2= (1 + 5)^2 = 36? No. 15^2 = 225   Then what is missing? A's place value of 10.   So it will be (10A + B) = (10*1 + 5)^2 = 225   So, in terms of AB, AB^2 = (10A + B)^2.   Answer: 1089.
<result>E</result>
† and ¥ represent nonzero digits, and (†¥)² - (¥†)² is a perfect square. What is that perfect square?