An estimate made by Abu Lughod indicated that the average number of indigenous Palestinians was about 420,000 in the West Bank and about 80,000 in the Gaza Strip by the end of 1948.
Schools and virtually every shop were closed in this city {Gaza City], where 420,000 people live.
Internal Displacement Monitoring Center, 2007:
Estimates of IDPs in Israel vary widely. There is no government or United Nations estimate. Sources for estimates are accademics, Palestinian NGOs and Israeli papers. The lowest estimate is 150,000 and the highest is 420,000, which includes the children and grandchildren of Arab villagers displaced in 1948, as well as Bedouin communities displaced later on.
Israel’s differential treatment in law, regulations, and administrative practice directly affect the roughly 490,000 Jewish settlers and 420,000 Palestinians in areas under its exclusive control in the West Bank (including in Area C and East Jerusalem).
The 420,000 Palestinians who currently reside in East Jerusalem possess permanent residency ID cards and are treated as foreign immigrants by the Israeli government. (The article predicted that Israel would take away the residency permits of all those Palestinians, a prediction that, like all of them, never came close to being true.)
Eurasia Review, 2018, headline:
What’s Behind The ‘Disappearance’ Of 420,000 Palestinians In Lebanon?
WASH Cluster, State of Palestine, 2020:
WEST BANK: 482,509 of people suffering limited access to water; 420,000 persons consume less than 50 l/c/d.
OpenDemocracy, April 2020:
Palestinians in East Jerusalem: living under a deadly virus and a violent occupation: "There is inescapable and particular on-going acute anxiety about the future of these 420,000 Palestinians."
World Food Programme, August 2020:
In support of the MoSD’s response plan, which estimated that 70,000 families (420,000 people) have been affected by the spike in COVID-19 in Gaza...
UNRWA is a lifeline to nearly 420,000 of the most vulnerable Palestine refugees in Syria.
Jeff Halper in Arena, June 2021:
Of the 150,000 Palestinians who remained in the country, the war displaced 30,000 to 40,000. Not allowed to return to their homes (which were either demolished or turned over to Jewish Israelis) and wanting to remain sumud (steadfast) near their lands, this population of internally displaced Palestinians has today grown to 420,000.
Middle East Monitor, July 2022:
The Nakba resulted in 750,000 Palestinians being driven from their homes; the 1967 Naksa saw another 420,000 forced to leave.
Since the attack, Israeli forces have imposed a continuing blockade on the area around Nablus, restricting the movement of about 420,000 Palestinians, including patients, elderly people and children, who must wait for hours before being able to cross.
“This year, actually over, since the beginning of my mandate [May 1, 2022], I have borne witness to a series of deeply distressing events. 420,000 Palestinians, including 91 children, and 56 Israelis, including five children, have been killed. ”
(She later walked this back, saying the number was 426.)
That's 14 separate times, in different contexts, that "expert" quoted a figure of 420,000 Palestinians.
I am not saying this is a conspiracy or anything like that. It is just a very strange coincidence for that number to pop up in such disparate ways.
420,000 seems like a more realistic, solid estimate than "400,000" or "450,000."
(h/t Irene)