7. Write the number 0.21212121 ... as a fraction.

Let x =

100x =

100x - x =

99x =

x=

So 0.2121 ... is equal to

21 / 99

Step-by-step explanation:

You want to get rid of the decimals so

Let x = 0.21212121

then 100x = 21.21212121

then 100x - x = 21

99x = 21

x = 21 / 99

So 0.2121 ... is equal to 21 / 99