What is the range and domain of the following functions:?

1. A function that assigns to each nonnegative integer its last digit

2. The function that assigns the next largest integer to a positive integer

3. The function that assigns to a bit string the number of one bits in the string

4. The function that assigns to a bit string the number of bits in the string.

I really haven't a clue for the last two, but these are my guesses for the first two:

1. Range: Non-negative integers, Domain: Non-negative integers less than 10.

2. Range: Non-negative integers, Domain: non-negative integers greater than zero.

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