A positive integer, if 100 is a perfect square, if 168 is another perfect square, then the positive integer is______ .

A positive integer, if 100 is a perfect square, if 168 is another perfect square, then the positive integer is______ .

Let the number be n. from the meaning of the question, we can get: n + 168 = A2 (1)n+100=b2… (2) (1) - (2), 68 = A2-B2 = (a + b) (a-b), because 68 = 1 × 68 = 2 × 34 = 4 × 17, there are only three cases, namely: ① a + B = 68, A-B = 1; ② a + B = 34, A-B = 2; ③ a + B = 17, A-B = 4; because ① A and B have no integer solution, exclude; ② calculate a = 18, B = 16, so: n = 182-168 = 162-10 = 156; ③ A and B have no integer solution, exclude To sum up, only n = 156, that is, the number sought. So the answer is: 156