The numbers just never add up because the idea that there were less than 144,000 Christians from the first century until 1935 is countered by what the WTS has published in their own literature.
They published an article about the ten persecutions than took place from the first century to somewhere around 303 A.C. and the number of Christian martyrs just in the last one by Diocletian was over 850,000. These Christian martyrs were held up as examples for modern day JWs to imitate. But they must have realized their goof, or someone actually did write in about it, because a few months later there was one of the QFR that explained that the majority of those Christian martyrs they had praised so highly were actually just "professed" Christians, i.e. not true Christians at all.
[wt 9/1/1951 Hated For His Name, p.516-519] Diocletian assumed the crown A.D. 284. At first he seemed friendly to the Christians, but in the year 303 he gave in to persuasion and opened the tenth persecution, probably the most ferocious of all. Suffocation by smoke, forcible drinking of melted lead, mass drownings and burnings, breaking on the rack of men and women alike ran the empire with blood. In a single month 17,000 were slain. In the province of Egypt alone, 144,000 such professed Christians died by violence in the course of this persecution, in addition to another 700,000 who died as a result of fatigues encountered in banishment or under enforced public works.
But someone noticed something about the numbers:
[wt 1/15/1952 QFR] Questions From Readers
● According to the article “Hated for His Name” in the September 1, 1951, Watchtower, hundreds of thousands of Christians died in the “ten persecutions” starting in Nero’s time, 144,000 dying in Egypt alone during one of the persecutions. How can this be harmonized with the Scriptural limitation of 144,000 placed on the number being in Christ’s body, andwhich position was the only one open to Christians during those centuries?—J.A., Dominican Republic.
The article did not class with any finality the individuals that died during these persecutions, but spoke of the results in a general way. Note that a key qualification was made in the case referred to in the question: “In the province of Egypt alone, 144,000 such professed Christians died by violence in the course of this persecution, in addition to another 700,000 who died as a result of fatigues encountered in banishment or under enforced public works.” The victims are identified as “professed Christians”, not Christians in fact. Many of those persons might have been caught in the wave of persecution, but may never have actually preached the truth or followed in Jesus’ footsteps, being only professed Christians. They knew the world they lived in was rotten and they were listening to the message of the Christians and willing to die for it even though not in line for the high calling in Christ Jesus. Many professed Christians today might be willing to die for their faith, but still not be Jesus’ footstep followers and meeting the Scriptural requirements for such.