How to fit multiple small photos in one picture?

Question

GIMP

For example, there is a photo 3 by 4. How to place it several times at 10 by 15?
Preferably without plugins, but quick and easy.

Answer 1

10x15 cm, and the photo is 3x4cm
In landscape orientation, these are 3 photos horizontally and 3 vertically
, 1 cm horizontally and 3 vertically remain - hence the side margins are 5mm each, and the top and bottom are 1 and 2cm, while placing the photo close - in paint or Word by selecting the appropriate paper 10x15 (or its inch equivalent)