Convert 111.101\(_{\text{two}}\) to a number in base 10.
A
6\(\frac{5}{8}\)
B
9
C
7\(\frac{5}{8}\)
D
8
Verified Correct Answer: C.
Step-by-Step Mathematical Solution
111.101\(_{\text{two}}\) to a number in base 10.
Use the successive multiplication method.
111.101\(_{\text{two}}\) = 1 x 2\(^2\) + 1 x 2\(^1\) + 1 x 2\(^0\) + 1 x 2\(^{-1}\) + 0 x 2\(^{-2}\) + 1 x 2\(^{-3}\)
= 1 x 4 + 1 x 2 + 1 x 1 + 1 x \(\frac{1}{2}\) + 0 x \(\frac{1}{2^2}\) + 1 x \(\frac{1}{2^3}\)
= 4 + 2 + 1 + \(\frac{1}{2}\) + 0 + \(\frac{1}{8}\)
= 7 + \(\frac{4 + 1}{8}\)
= 7 + \(\frac{5}{8}\) = 7 + 0.625 = 7.625
Source: WAEC / JAMB / NECO Classroom Archive (Record #78181)