Go to the site I referenced in the prior post, plug in the numbers including the date on the pack and see how many cells you need and get from a starter.
177-199 billions depending on the original gravity
but look what they say on their website:
Activator Product Information and Usage
Activator packages are designed for direct inoculation of 5 gallons of standard* wort. Activator packages contain live yeast cells in a liquid slurry. This yeast slurry is packaged in an optimum condition for storage, while maintaining the ability for rapid and complete fermentation.
Activator packages include a sterile liquid nutrient pouch that, when smacked, releases its contents into the yeast slurry and activates the package. The available nutrients initiate the cultures metabolism which in turn generates CO2 and causes swelling of the package. This process will reduce lag times by preparing the yeast for a healthy fermentation prior to inoculation. Activation also serves as a viability test of the culture. Expansion of the package is an indicator of healthy (viable and vital) yeast. Although beneficial, cultures do not need to be activated prior to inoculation.
Usage
The Activator package contains a minimum of 100 billion cells in a yeast slurry.. The Activator is designed to directly inoculate 5 gallons of standard strength ale wort (1.034-1.060 SG) with professional pitching rates. For lagers, we recommend inoculating the wort at warm temperatures (68-70°F/ 20-21°C), waiting for signs of fermentation, and then adjusting to the desired temperature. Alternatively, for pitching into cold conditions (34-58°F/ 1-14°C) or higher gravity wort, we recommend increasing this pitching rate. This can be achieved by pitching additional Activator packages or by making a starter culture. Please see the Pitch Rate section for additional information.
Full swelling of Activator packages is not required for their use. The contents of Activator packages may be direct-pitched without prior activation. Our smack pack technology is intended to be a tool for your use in determining viability, and in initiating metabolism for faster starts to fermentation.
Best if Used by: This package is best when used within 6 months of the manufacturers date when stored between 34-40°F (1-4°C). Older yeast or yeast that has been exposed to higher or lower temperatures may take longer to become active or swell.