Alt+H, A, then C is to center align the contents.
Step 1: Click any cell in the worksheet (e.g., A1);
Step 2: Press the Alt key, and you will see the access key on each tab;
Step 3: Click the letter H from the keyboard, and the Home tab will open.
Step 4: Click the letter A;
Step 5: Click the letter C, and the contents are center align now.