function prost (n : integer) : boolean;
var  r : integer;
begin
if n<2 then result:=false
else
 begin
  r := 2;
  result:=true;
  while (r*r<=n)and result do
  if n mod r=0 then result:=false
  else inc(r);
 end;
end;

procedure Execute;
for i:= Low(ArrNumber) to High(ArrNumber) do
  Work(ArrNumber, i);
ArrNumber:=nil;
end;

procedure Work(ArrNumber: TarrNumber; var AIndex: integer);
var
 DKey: string;
dt: TDateTime; 
begin
  DKey:= '';
  
  DKey:= intostr(AIndex) + intotstr(AIndex+1) + inttostr(AIndex+2); //если закоментировать, то загрузка ЦП 80-90%

  if prost(ArrNumber[AIndex]) then dt:=0 
  else dt:= 1;
end;