The state tax commission petitioned for a writ of mandamus requiring the respondent county clerk of Buchanan County to compute and extend taxes for 1975 based on an aggregate valuation of real and tangible personal property as determined by the commission under § 138.390 and § 138.-400(3), RSMo 1969. Sections 137.235, 138.-060 and 138.080, RSMo 1969, impose a duty upon the county clerk to comply.

This case, which has been briefed and argued, is another in a series of cases where there is a reluctance on the part of the county clerk to follow through on computing and extending the taxes so as to meet the aggregate valuation in the county as fixed by the state tax commission, and the outcome is determined by application of the rules and principles set forth in earlier cases. State ex rel. State Tax Commission v. Briscoe, 451 S.W.2d 1 (Mo. banc 1970); State ex rel. Riney v. Anderson, 536 S.W.2d 161 (Mo. banc, 1976). As has repeatedly been declared, the duty of the county clerk to comply with the orders of the state tax commission is ministerial, clear and unavoidable. The fact that the abstract of taxable property originally returned by the clerk to the commission under § 138.390, supra, contained a valuation error of ap*182proximately four and one half million dollars which was not discovered by the clerk’s office until the individual tax statements were almost in readiness for mailing does not excuse the clerk from complying with the commission’s order equalizing the valuation. The clerk is required to proceed with extension and computation of taxes on the valuations of real estate at $117,372,660, in compliance with figures set forth in the commission’s amended order of June 27, 1975.

Writ made peremptory.