(a) Except as otherwise provided in subsection (b) of this section, wages, for all purposes of this chapter, shall be determined on the basis of earnings of the worker, at the time of injury, from the employer liable to pay compensation, except that, in the case of employees whose tenure at the time of injury was less than one month, the weekly wages of such employees shall be determined by the Administrator on the basis of weekly wages for permanent employment of similar character. Special overtime rates shall not be taken into account unless earned regularly over a period of two months immediately preceding the accident. Compensation for any fractional portion of a week shall be computed on the basis of the working days involved.
(b) In the case of part-time workers or workers holding jobs with two or more employers wages, for the purpose of computation of benefits only, shall be the greater of (1) the weekly wages for permanent full-time employment of similar character or (2) the actual total wages received from all of the worker's employers legally required to be insured.