Not sure but I think it’s B
Answer:
The number of possible three-digit phone prefixes that are used to represent a particular geographic area is 640.
Step-by-step explanation:
The phone prefixes used to represent a particular geographic area are a 3 digit code consisting of numbers from 0 to 9.
The prefix code are of the form: <u>x</u> <u>x</u> <u>x</u>
Condition: The first or the second place cannot take values 0 or 1.
Then the first place can be occupied by the remaining 8 digits.
Similarly the second place can also be occupied by the remaining 8 digits.
And the third place can be occupied by any of the 10 digits.
So the number of ways to construct a phone prefix for any area is:

Thus, the number of phone prefixes possible for any area is 640.
Answer:
Step-by-step explanation:
Divide the tens column dividend by the divisor.
Multiply the divisor by the quotient in the tens place column.
Subtract the product from the divisor.
Bring down the dividend in the ones column and repeat.
okay so look at the image down below