The answer depends on the context. Some examples:
In algebra z is a variable. What z equals would depend on the math problem you're doing and what the answer to that problem is.
a math equation
ask your math teacher
The product in a math is the answer to a multiplication problem.
zero
In algebra z is a variable. What z equals would depend on the math problem you're doing and what the answer to that problem is.
It represents a number.
z = 1/2
The equation z-19 time 34 is a verbal sentence. This a math problem.
zero z-coordinate on a z-axis, zilch, zombie (math student)
the only math words i know that start with the letter z is z intercept, z-axis and zero
each # in math can represent a letter Y is second to last letter so Y equals 6.2 or 2.0 it depends on the problem. <3
a math equation
It depends on which country are you living in. philippines
The aftermath
The answer may depend on what the cards represent, but it is unlikely that any set of cards will cover all aspects of mathematics.
ask your math teacher