Hold a tape measure over the cement pavers and draw a line with a permanent pen or black crayon where you want to cut.
Connect a masonry blade or a diamond-tipped blade to a circular saw according to the saw's instructions. Check that the saw is turned off and unplugged to insure your safety. Fix the blade depth to 1/2 inch. Gently tug on the blade to check that it's secure.
Plug in the circular saw and position the cement on the ground or a surface that the blade won't damage, like a saw table.
Hold in the trigger to start the blade and move it slowly toward the chalk line on the cement. Hold the circular saw firmly in place while the blade is moving and run it slowly across the chalk line.
Reset the blade depth on the saw to 1 inch and move the saw through the pre-cut chalk line. If the cement is thin, it should split in half after the second cut. If it's thick, flip the cement over and re-set the blade depth to 1/2 inch. Cut the cement from the other side at 1/2 inch and then 1 inch if necessary.
Draw a cut line over the whole cement paver over the top and bottom and both edges with black crayon or chalk.
Place a cold chisel over the mark and tap it with a hammer. Chip the marked line over the paver around the entire paver.
Hammer the chisel on the side you plan to discard so it will break over the chipped line. If the paver doesn't crack, make the chips around the cut line deeper and strike it again until it splits in two.