Don't waste your package yeast. After you have added yeast to some bread dough, pinch off one handful of the bread dough after the first rise and save it in an airtight container in a cool dark place. The next day thoroughly mix (knead) the old dough into a new batch of dough. The yeast will multiply and spread throughout the new batch. After the first rise, pinch off a handful of dough and save it. Continue this process each time you make yeast bread and you will be able to make bread for a very long time from that one original package of yeast.