(A) Express the number $47$ in binary number.
(B) Express the binary number ${110,111}_2$ in decimal system.

• $\left(A\right)$ $47$ can be written as $32+8+4+2+1$
• Therefore it can be written in binary form as ${101111}_2$
• $\left(B\right)$ ${110111}_2=32+16+0+4+2+1=55$