#1/3 = 0.3333...#
#1 = 3/3 = 3 * 1/3#
#1/3 * 3 = 0.3333... * 3#
#0.333.. * 3 = 0.9999...#
#1 = 0.9999....#
#0.3333..# is the decimal notation for #1/3#. the #3# in #0.3333...# is recurring.
#1# is #1/3 * 3#.
since #0.3333..# is the decimal notation for #1/3#, #0.3333...# can be multiplied by #3# to find #1# in decimal notation.
#0.3333...# mulltiplied by #3# is #0.9999....#
with more #9#s in #0.9999...#, it gets closer and closer to #1#.
when the #9#s in #0.9999...# are infinite, the number is said to equal #1#.
this makes #0.999...# suitable repeating decimal notation for #1#.