It happens quite usually with simple sanding papers or stronger ready made, to get torn very easily and you have to subsitute with the cost of buying new and new ones to finish your work.
Even the cheapest sanding papers (those you fold and cut in threes) can be more durable and much more effective in your sanding. You will discover yourself how simple it is.
Cover their back sides with a transparent self-adhesive plastic roll, (like the one you cover paper surfaces).
You can arrange the sanding papers on their backs to be stuck on the adhesive, side by side, different grade, various purpose etc
Transparent adhesive is preferable because you can easily identify the grade number of each piece then.
You can do this on the same roll and for once for your convenience.
Do it before you need them.
Cut in pieces and keep them in your drawer for the moment you need to substitute, change grade, and when you are very busy to have a durable sanding paper.
The profit out of this is saving time and most important (!) THE SCISSORS ARE GETTING A NEW LIFE (!)
You will discover that automatically it gets A SHARPENING effortlessly!!!