What is the plural for No.?

Answer 1

The plural form for the noun 'no' is 'nos' or 'noes'. Both are accepted forms. Example sentence:

How many nos will it take before you stop asking?

noes [nouz] - pronounced like knows or nose

* following the rule that plural of nouns is formed by adding -es instead of -s if it ends with -o

* all this assuming you are asking for a plural of "no" as an expression instead of "negative answer", thus a noun, because a negation itself (no) doesn't have a plural. (e.g. There is no answer. There are no answers.)

The confusion of yesses and noes is often avoided by using "yeas" and "nays".