Having a hard time remembering how many shaves you've got on a blade? What about multiple razors? Confusing, isn't it?
Here's a simple trick that will solve that problem super easy!
Use a regular six-sided die. Yup, it's that simple. Every time you shave, rotate it to the next higher number. If you've got more than one #razor, use multiple dice - either in a particular order or a different color. If you tend to shave more often on a blade, perhaps because you use a single-edge razor, use gaming dice. They come in four, six, eight, ten, twelve and even twenty or a hundred sides. Though the latter is more of novelty; it's practically round and dimpled like a golf ball!
This solution is simple, cheap and you can set your die/dice on a counter or on a shelf (like in a medicine cabinet) somewhere!