To put it simply, there is a trademark not far above the keys. Directly in front of the trademark is the middle C, which is the commonly used 1234567. As for the black keys, they are all changed. For example, the black key closest to the right of C is sharp. C starts from the center C and goes to the right, which is 1, #1, 2, #2, 3, 4, #4, 5, #5, 6, #6, 7, 1, ...starts from the center C and goes to the left. That's 1, 7, #6, 6, #5, 5, #4, 4, 3, #2, 2, #1, 1, ...