In the octal system, 4 occupies the same sort of position as does 5 in the decimal system; that is 4 is (1)/(2) of the octal base just as 5 is (1)/(2) of the decimal base. Therefore,
.48 = (1)/(2) = .510.
Since .48 = (1)/(2), .448 is more than (1)/(2), isn’t it? And thus 21.448 is closer to 228 than to 218.
Now return to Page 241 and select the correct answer.