The subnet mask on the serial interface of a router is expressed in binary as 11111000 for the last octet. How do you express the binary number 111110

The subnet mask on the serial interface of a router is expressed in binary as
11111000 for the last octet. How do you express the binary number 11111000 in
decimal?

A. 210
B. 224
C. 240
D. 248
E. 252
Answer: D
Explanation:
128 + 64+32+16+8 = 248. Since this is the last octet of the interface, the subnet mask
would be expressed as a /29.
A groan grasps the peanut near the offending anthology.