Answer:
32
Step-by-step explanation:
Totally there are 50 tosses.
Let the number of tosses which resulted head be x.
Therefore the number of tosses which resulted tail is 50−x.
We get x×1+(50−x)×(−1)=14
x−(50−x)=14
x−50+x=14
x=32
It was would numbers 000-000-0000 through 999-999-9999. So that would be 9,999,999,999 + 1 = 10 billion different 10-digit phone numbers.