$data = Get-ItemProperty "HKLM:\Software\Microsoft\Microsoft Antimalware\Scan" | Select-Object -ExpandProperty LastScanRun
$time = [DateTime]::FromFileTime( (((((($data[7]*256 + $data[6])*256 + $data[5])*256 + $data[4])*256 + $data[3])*256 + $data[2])*256 + $data[1])*256 + $data[0])
Get-Date $time -Format "mm/dd/yyyy"