This is the first - presumably simplest - puzzle of an intended series of numerical dissection puzzles.
The goal is to dissect the 15 x 11 number-grid below into exactly 17 rectangular sub-grids.
- Each rectangle has to be of shape of either ( ? x 3 ) or ( 3 x ? ) number squares.
- Each rectangles has to fulfil either a sum-equation or a difference-equation
using its 3 rows or 3 columns, respectively.
- Numbers are either read "left-to-right" or "top-to-bottom" and never "right-to-left" or "bottom-to-top".
- Leading zeros are acceptable.
Please also describe in your answer any "technique" or "routine" you have used to find the solution.
Examples of valid 'rectangles':