Late at night, after the measurements are done, pixel Marie Curie likes to sit in the dark laboratory shed and watch the faint glow of her samples on the shelves. Tonight she has set herself a puzzle called Glow Jar Sums: a special jar on the bench will only shine if she feeds it the right numbers.
Every correct answer makes the jar glow a little brighter, every streak sends ripples of light along the shelves and a single wrong answer lets the glow fade away. Fill the jar to the brim and the whole shed lights up like a starry sky. Stop short, and the experiment will have to wait until tomorrow night.
