Question

The function that assigns to each positive integer its largest decimal digit... Find the domain and the range

Answer 1

Well, as you said, it only assigns a value to each positive integer, so I guess the domain is the set of positive integers
\[\huge \mathbb{Z}^+\]

Answer 2

That i can get but what would be the range? if there is any

Answer 3

Of course there is :)
Keyword here is that the value assigned to any positive integer is the value of its largest digit. So it can only be a digit, right?

Answer 4

Digit --> single digit number
Just to be clear.

for instance
f(362) = 6
because the largest digit is 6.

Answer 5

Ohhh
I( get it now!!!

Answer 6

Remember, your range may be single digits, but
0 is not included :)

Think about it.. there is no positive integer where 0 is its largest digit, right? ;)

Answer 7

but it says its largest decimal digit wouldnt that change everything

Answer 8

It wouldn't, it just takes the largest digit.

Answer 9

true

Answer 10

ohhh i see
okay okay this makes perfect sense thanks alot man!

Answer 11

So your range is this finite set
{1,2,3,4,5,6,7,8,9}
:)

Answer 12

No problem :)

Answer 13

SO the domain and range would just about be the same

Answer 14

No, far from it, the domain can be ANY positive integer at all, which means there are infinitely many possibilities, while your range can only ever be one of the nine nonzero digits :)

Answer 15

Ohhh yeah true i overlooked that!

Answer 16

Okay
this makes sense
now

Answer 17

perfect

Answer 18

Awesome :)
Don't I just love it when things make sense :)

Answer 19

we both do lol