Position one image in the corner of the page, than use CTRL Arrow to align the images in the columns and rows separately
Terry is right, and I just refreshed my memory.
You don't even have to position the first image to a corner.
You can align subsequent images to the vertical edge (one below the other), or the both planes.
Just align your first image paying attention to the rulers at the top and sides, so you can accurately place it.
Then select the next, and tap CTRL Arrow in the direction you want to go, and it aligns itself to the first image.
Pretty neat trick
Fred