The equal sign with the slash means "is not equal to".
By 'an equal sign with a lightning bolt [through it]', do you mean '≠'? That means 'not equal to'. For example, 6≠9.
It means the figures on either side of the equal sign have equal values to each other.
"is equivalent to"
not equal to
It means "not equal to".
If you mean in Excel, yes: you must always start a formula with an equal sign.
Did you mean this? ≟
It means congruent
it means: "does not equal to" it mean that it is not equal to that, like 4a isn't equal to 5g. teehee!
A formula with an equal sign
Equals sign demonstrates that something is the same as something, or equal to.