.

Also question is, what does ∀ mean?

∀ This symbol means for all (or sometimes, for every). For example, “∀ squares D, D is a rectangle”. This symbol means there does not exist. For example, “ a unicorn”. (yet) Symbols for dealing with elements and sets ∈, /∈ The symbol ∈ is used to denote that an element is in a set.

One may also ask, what is inverted A? Inverted A sysmbol denoted the expression “For all” For example, to say For all x={even number} meaning for all values of x when x is even.

Simply so, what is an upside down A in math?

The upside-down A symbol is the universal quantifier from predicate logic. (Also see the more complete discussion of the first-order predicate calculus.) As others noted, it means that the stated assertions holds "for all instances" of the given variable (here, s).

What does C mean in numbers?

And thus 60, 70, and 80 are LX, LXX and LXXX. C. C stands for centum, the Latin word for 100. A centurion led 100 men. We still use this in words like "century" and "cent." The subtraction rule means 90 is written as XC.