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Edit summary for version 12 :

Version 11

Version 12

Idiom #65 Format decimal number

From real value x in [0,1], create its percentage string representation s with one digit after decimal point. E.g. 0.15625 -> "15.6%"

Idiom #65 Format decimal number

From real value x in [0,1], create its percentage string representation s with one digit after decimal point. E.g. 0.15625 -> "15.6%"

Code
var s = "${(x * 100).toStringAsFixed(1)}%";