Read the given sentences and choose the verbs that agree with the nouns.
No one in the class ____ a calculator.

The correct answer is: Has

The correct answer is "Has".
Here, the ownership of calculator is to be mentioned and we know that "Have" verbs indicate the ownership of something. The sentence is in present tense and the pronoun "No one" is third person singular number. A pronoun functions exactly as a noun so the same rule will follow here. So, the correct answer is "Has" ("Has" is used for third person singular and for the rest, "have" is used).