Edit.... gazumped, but to extend the previous post
4.16.2 For three digit numbers, the second and third numbers are grouped. Examples are as follows:
Sunstate 122 SUNSTATE ONE TWENTY TWO
Eastern 1220 EASTERN TWELVE TWENTY .........
(Qantas 7624 QANTAS SEVENTY SIX TWENTY FOUR
)
4.16.4 A pilot not using "group form" in establishing communication, but subsequently addressed by ATS in this format, should adopt the use of "group form" for the remainder of the flight in Australian airspace"