March&June 2016 Q1 consolidated statement of cash flows

Hi sir, I am stuck in working 3, depreciation in proceeds on disposal of Northern. I have been told the fair value uplift of $16m in relation to plant with a remaining useful life of eight years. Since, the disposal happens on 31 July 2015, I calculate the depreciation in this way: $16m/8years*6/12=$1m. Even the result is the same as the answer. I am just wondering where the 4/8 come from in the answer? ( 4/8 depreciation) Many thanks