👉 Masked is a type of mask or device used in medical procedures, often for visual inspection of tissues or organs, but it can also refer to an invisible or shadowy appearance, such as in a mask during surgery or a projection mask used in film.
👉 In mathematics, a "masked" number is an integer that is not expressible as a sum of two or more non-negative integers. For example, 367 (which can be expressed as 21 x 14 + 5) and -90 (-10 x 9 + 8) are both masked numbers. The term "masked" comes from the fact that when we express a number in terms of non-negative integers, it is possible to assign each digit