Intel's own 1994 White Paper estimated an average Pentium user would encounter the FDIV bug about once every 27,000 years

pentium-fdiv-bugsb94intelquantitative-claimrisk-communicationhistory-of-computing

Sharangpani and Barton's 1994 Intel White Paper — the primary document underneath the confirmed cause of the Pentium FDIV bug — states its own headline risk-communication figure directly, in Section 6.2.1: "an average PC user invoking 1,000 divides per day would see a FIT rate of once in 27,000 years due to this failure mechanism." Table 5-1 and item 2 of the report's Conclusions both restate the identical figure in near-identical wording ("The average PC user is likely to encounter a failure once in 27,000 years due to this flaw"), so it is not a one-off phrasing but the number Intel repeated across the document as its case that the flaw was inconsequential for ordinary use.

This is Intel's own defense of the chip, not a secondary's summary of that defense — the number that IBM's independent risk analysis publicly disputed weeks after this paper circulated, when it halted Pentium shipments over a claimed error rate thousands of times higher than Intel's. The 27,000-year figure and the IBM dispute are two ends of the same argument: how often "1,000 divides per day" and "random operand" actually describe real workloads, a modeling assumption the flaw's low overall probability (see claim-pentium-fdiv-bug-five-missing-srt-lookup-table-entries) does nothing to settle on its own.