Zollars

Zollars (also known as Dollars, Cash or Money) are the main form of currency in the world of Zombie HQ.

Collecting and Using Zollars
Despite being the main form of currency in Zombie HQ, Zollars are extremely common and can be found in every single mission in the game. To compensate for this, however, Zollars need to be amassed in large amounts if the player wants to buy anything expensive early in the game. Later on, Zollars become worth more and drop in larger amounts, but the player still needs to earn their new gear. Zollars can drop or otherwise be aquired from multiple sources:
 * From dead zombies (seems to be more common when they are blown up rather than shot)
 * Randomly scattered around the area (usually out of reach of the survivor, meaning that they need to be tapped on to be collected)
 * From Beasts
 * From Furniture
 * As a post-mission reward
 * From the Slot Machine
 * From in-game adverts (if the player chooses to watch one, they recieve Z400)
 * After - or during - looting an object
 * From reparing barricades
 * After airlifting two, five or ten survivors
 * For completing tasks
 * When the player levels up
 * From the currency shop (you filthy cheater)

Value
The value of a Zollar is nowhere near the same as the value of an American Dollar, despite being strikingly similar forms of currency. Some quick calculations can reveal how much a Zollar is really worth:

In Zombie HQ, an AK-47 is worth Z60,000.

In real life, a good-quality AK-47 from a mediocre manufacturer can be worth around $575.

575 ÷ 60,000 = 0.00958333333

Therefore, a Zollar is worth (when rounded) 0.01 of one American Dollar, requiring roughly 100 Zollars to equal a dollar. This in turn means that a Zollar is roughly one Cent in value, although that's only the case if you use rounding throughout the equation.

Obviously, the value may change when based off other items in Zombie HQ, but that is simply due to game design.