write the repeating decimal 0.64 as the ratio of two integers

Answer 1

You mean 0.6464646464646..... ??
64/100 + 64/100 00 + 64/100 00 00
geometric sequence
a = 64/100
r = 1/100
sum = a/(1-r) = 64/100 / (1 -1/100) = 64/100 / 99/100
= 64/99