Decadic number

What is the expanded form of this number?

18.029

A: (1x10)+(8x1)+(2x1/10)+(9x1/100)
B: (1×10)+(8×1)+(2×1/10)+(9×1/1,000)
C: (1×10)+(8×1)+(2×1/100)+(9×1/1,000)
D: (1×10)+(8×1)+(2×11/00)+(9×1/100)

Correct answer:

x = C

Step-by-step explanation:

$$\begin{gathered} A=(1\cdot 10)+(8\cdot 1)+(2\cdot 1/10)+(9\cdot 1/100)=\frac{1829}{100}=18\frac{29}{100}=18.29 \\ B=(1\cdot 10)+(8\cdot 1)+(2\cdot 1/10)+(9\cdot 1/1000)=18.209 \\ C=(1\cdot 10)+(8\cdot 1)+(2\cdot 1/100)+(9\cdot 1/1000)=18.029 \\ D=(1\cdot 10)+(8\cdot 1)+(2\cdot 1/100)+(9\cdot 1/100)=\frac{1811}{100}=18\frac{11}{100}=18.11 \\ x=C \end{gathered}$$

Try another example