[tex]1ha = 100a[/tex]
[tex]1a = 100cm[/tex]
[tex]1km = 1000m = 100000cm[/tex]
[tex]6ha \times 5a \div 1cm + 123123 \times 7km = 600a \times 5a \div 1cm + 861861km = 3000a \div 1cm + 861861km = 300000cm \div 1cm + 861861km = 300000cm + 861861km = 3km + 861861km = 861864km[/tex]