“Ten times closer” is pretty unambiguously 0.1. What starts getting more confusing is “300% further” which is technically 4 but many understand as 3 (try replacing by 50%, 50% further is 1.5 not 0.5). Also “50% closer” being the same as twice closer while 50% further is only 1.5x further can get confusing too, and it gets even worse with “50% slower” - is speed now 1/1.5 (= it takes 50% more time) or 0.5/1 (= speed is reduced by 50%) ?
“Ten times closer” is pretty unambiguously 0.1. What starts getting more confusing is “300% further” which is technically 4 but many understand as 3 (try replacing by 50%, 50% further is 1.5 not 0.5). Also “50% closer” being the same as twice closer while 50% further is only 1.5x further can get confusing too, and it gets even worse with “50% slower” - is speed now 1/1.5 (= it takes 50% more time) or 0.5/1 (= speed is reduced by 50%) ?
Most of the time it is pretty easy to know what the winter is trying to imply.
It gets really silly when using big numbers. e.g. a nanometre is 100,000 times smaller than a human hair.