I assume his instructor (sounds like an assignment to me) wants a loop or something similar to be used so that it can be shown that they understand the logic behind the triangle...
You have to think about how the number of spaces and the number of digits relate to a loop.
You will need a loop to count through the number of lines.
Then you will need one or more "inside" loops to count off the spaces/letters to print.
Whenever I have to make characters line up a specifc way on the screen, I find it helpful to get out a piece of graph paper and a pencil and draw what I want to see, then count cells so I know how many times I need to loop, etc.
Good luck!
@berkcan
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What Duoas means by that is that you shouldn't just give them the code for it because then they'll never learn how to do it themselves and as soon as a problem comes along that they haven't done before, they won't be able to solve it.