In general, I think the FAR is fairly understandable, though the CAS requirements are an exception. I don't know any other FARs that include a math problem...
FAR 52.215-15 Pension Adjustments and Asset Reversions.
((2) For contracts and subcontracts that are not subject to full coverage under the CAS, the amount measured, assigned, and allocated in accordance with 48 CFR 9904.413-50?(12), except the numerator of the fraction at 48 CFR 9904.413-50?(12)(vi) shall be the sum of the pension plan costs allocated to all non-CAS covered contracts and subcontracts that are subject to Federal Acquisition Regulation (FAR) Subpart 31.2 or for which certified cost or pricing data were submitted.