The grid contains nine "doublers," one in each row, column, and 3x3 box; each digit from 1-9 is "doubled" exactly once. Doubled digits count as twice their value in the circles and on the arrows.
• Digits placed on an arrow must sum to the digit placed in that arrow's circle.
https://www.youtube.com/watch?v=avZsikpuxSQ&ab_channel=BremSterPuzzles
The grid contains nine "doublers," one in each row, column, and 3x3 box; each digit from 1-9 is "doubled" exactly once. Doubled digits count as twice their value in the circles and on the arrows. • Digits placed on an arrow must sum to the digit placed in that arrow's circle.