Open Middle Sum Problem

Creation of this [url=https://www.openmiddle.com/]Open Middle[/url] resource was inspired by this tweet from [url=https://twitter.com/kurt_salisbury/status/1312879416008151046?s=20]Kurt Salisbury[/url]. [br][br]Using the digits 1-9 at most 1 x each, fill in the top four (or bottom four) boxes to form four two-digit numbers that sum to 100. Each digit repeats once. You will see where it repeats after you start typing digits in the boxes. [br][br][color=#9900ff]You can create your own magic sum to try to reach by typing in the input box lower right. [/color]

Note: If you accidentally repeat a digit, one (or more) of them will disappear. If this happens, enter another digit inside one of the input boxes that became empty.

What is the [i]highest [/i]possible sum you can get here? How do you know?

What is the [i]lowest[/i] possible sum you can get here? How do you know?

Open Middle Sum Problem

Note: If you accidentally repeat a digit, one (or more) of them will disappear. If this happens, enter another digit inside one of the input boxes that became empty.

Information: Open Middle Sum Problem