Answer:
[tex]6 \times 10^{7}[/tex]
Step-by-step explanation:
Total number of toll-free area codes = 6
A complete number will be of the form:
800-abc-defg
Where abcdefg can be any 7 numbers from 0 to 9. This holds true for all the 6 area codes.
Finding the possible toll free numbers for one area code and multiplying that by 6 will give use the total number of toll free numbers for all 6 area codes.
Considering: 800-abc-defg
The first number "a" can take any digit from 0 to 9. So there are 10 possibilities for this place. Similarly, the second number can take any digit from 0 to 9, so there are 10 possibilities for this place as well and same goes for all the 7 numbers.
Since, there are 10 possibilities for each of the 7 places, according to the fundamental principle of counting, the total possible toll free numbers for one area code would be:
Possible toll free numbers for 1 area code = 10 x 10 x 10 x 10 x 10 x 10 x 10 = [tex]10^{7}[/tex]
Since, there are 6 toll-free are codes in total, the total number of toll-free numbers for all 6 area codes = [tex]6 \times 10^{7}[/tex]
