Numeric literals cannot contain dollar signs or commas, but they can be written in scientific notation : Introduction « PL SQL Programming « Oracle PL/SQL Tutorial

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SQL>
SQL> declare
  2  --    v_real1 NUMBER:=$123456.00; -- INVALID
  3  --    v_real2 NUMBER:=123,456.00; -- INVALID
  4        v_real3 NUMBER:=5e10;       -- VALID
  5        v_real3 NUMBER:=5e-3;       -- VALID
  6  begin
  7       NULL;
  8  end;
  9  /

PL/SQL procedure successfully completed.

SQL>
SQL>
SQL>

Oracle supports scientific notation for numbers between 1E-130 and 1E+126, where E stands for "times ten to the power of".