Another way to explain the 0.999... = 1 phenomenon is to go through fractional math.
Most people learn that 1/3 = 0.333... and can accept this
Most people then learn or understand that 2/3 = 2*1/3 = 2*0.333... = 0.666...
Continuing down that path, 3/3 = 3*1/3 ? 3*0.333... = 0.999...
And since early fractional math teaches you that 3/3 = 1 this leads us to the conclusion that 1 = 0.999...