How can hard code values in an internal table?

How can hard code values in an internal table?

I need to do the following>>>>

Put 1 into itab-num(01)(internal tables first row)

Put 2 into itab-num(02)(internal tables second row)

Put 3 into itab-num(03)(internal tables third row).

<b>PS:</b>I dont have option of fetching from a table after making entries of 1,2 and 3.

Regards,

Shashank.