I'd guess this has got this level of accuracy via back-and-forth mis-translation. "A good 2 metres" (as Flemish news is quoting) became "7.5ft" became "2.29m"

I'd guess this has got this level of accuracy via back-and-forth mis-translation. "A good 2 metres" (as Flemish news is quoting) became "7.5ft" became "2.29m" Or, if you can identify where a stone has been moved from and to, you can use the pre-installed iOS app 'Measure', which always gives you a number to the nearest cm over this distance.