These number puzzles are often referred to as "numerical crosswords".

How to play

View the video on YouTube with subtitles/closed captions

(If the captions don't appear, tap the ⚙️ icon on the video to select playback options.)

Use the number clues in the triangles to deduce which numbers go in the grid. Only the numbers 1-9 can be used and cannot be repeated within the same line segment (i.e. as part of the same clue answer). The numbers entered in each line segment must add up to the number in the clue.
Tap on a grid square to select it, then use the keypad buttons below the grid to enter numbers.
The top row of buttons enter numbers in pen (indicating that they're part of the final answer). The bottom row allow you to enter numbers in pencil, to mark which numbers are still valid for that square.
You can erase numbers you've entered by reselecting the square you want to edit, and using the keypad buttons to 'switch off' (erase) entered numbers.
The clue triangles will light up GREEN if the numbers in that line section add up to the clue number, and RED if they don't. Please note that these indicators only show if the answer you've entered is valid, and not whether it's correct as part of the complete puzzle.
For example, if the clue number is "4", and you have entered "2" and "2" in adjacent boxes, this will still light up as green, even though (as per the puzzle rules) a line segment cannot contain the same number twice.

Extra help

If you're stuck on a Kakuro puzzle, you can use coins to buy hints.
Hints can be used by tapping on the relevant icon in the status bar area at the top of the screen.
The cost (in coins) to use each hint is printed under its icon.
■ Solve Cell
Use this hint to put the right number into the currently selected cell only.
■ Show Pencil Numbers
Use this hint to fill in all pencil marks showing which possible numbers are valid in each location.
■ Check for Errors
Use this hint to highlight all the cells with incorrect values.