Question

can someone correct this for me parts A-E and if i am wrong can you help me....please

How many 7-digit telephone numbers are possible if the first digit cannot be zero and.....
a) only odd digits may be used?
my answer: 8125

b) the telephone number must be multiple of 10(that is , it must end in zero)?

my answer: 1,000,000

c) the telephone number must be a multiple of 100?

my answer 100,000

d) the first 3 digits are 481?

my answer 10,000

e) no repetitions are allowd?

my answer: 120

I will be happy to critique your work.