Marjon,

Let's try something a little simpler.

Find the sum of all the 2-digit positive numbers with no zero digit.

I can write them down, well I can at least start

11
12
13
14
15
16
17
18
19
21
22
23
.
.
.

Suppose I have written them all. Look at the tens column. How many ones are there? How many twos? How many threes?

Now look at the units column. How many ones are there? How many twos? How many threes?

Now can you solve the original problem?

Penny