Can a math error on a purchase void the contract?

Yes, a math error on a purchase can potentially void the contract, particularly if the error is significant and one party can demonstrate that it led to a misunderstanding or misrepresentation of the terms. Generally, contracts require a meeting of the minds, and if one party can prove that the error affected their decision to enter into the contract, they may have grounds to void it. However, minor errors may be corrected without voiding the contract, depending on the circumstances and the intentions of the parties involved. Legal advice is recommended in such situations.