Observe the following column number: - 1, 2, - 3, 4, - 5, 6, - 7 Let AIJ be the number in row I and column J, for example, A23 = 4, then A87 is______ ．

Observe the following column number: - 1, 2, - 3, 4, - 5, 6, - 7 Let AIJ be the number in row I and column J, for example, A23 = 4, then A87 is______ ．

According to the absolute value of the last number in each row is the square of the number of rows n in this row, so the absolute value of the last number in the eighth row is: 8 × 8 = 64, so the number in the eighth row and the seventh column is: 56, so the answer is: 56

It's an even number. It's a multiple of two and three. It's a multiple of five after a two digit number and a ten digit number

54　　　　

I am an even number and a multiple of 2 and 3. I am a two digit number. The number of one digit is a multiple of 5 after swapping with the number of ten digits

54

This is an even number, which is a multiple of 2 and 3, and also a two digit number. After the exchange of one digit and ten digit number, it is a multiple of 5. What is the number?

The answer is 54