If an operation is performed on any two numbers in a set and the result is still in that set, we say that the set is closed under that operation. For example, we can say that the set ofpositive integers is closed under additionbecause if we add any two positive integers, the result is still a positive integer. On the other hand, the set of positive integers is NOT closed under subtraction because in many cases, the result is a negative integer (e.g 9 – 12 = -3). The video below is one of the best videos I’ve seen so far explaining closure property This video is just one of a series of videos about Imaginary Numbers.
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More than a year ago, I shared to you Genius Scan, a portable scanner app. There is also a similar app called Tiny Scanner which is both available as iOS and Android Apps.
Tiny Scanner is an app that turns your iOS or Android device into a portable scanner by letting you take a photo of a document and saving it as PDF or as images.
Courtesy of iTunes
The app has the following notable features:
detects page edges automatically
pages can be set in different sizes (Letter, A4, Legal, and more).
images can be scanned in color, grayscale, or black and white
it has 5-levels of contrast for monochrome texts.
documents can be protected by a pass code.
available for both iPhone and iPad
Documents produced by Tiny Scanner can be shared through Email, Dropbox, Evernote, Google Drive or Box.
Tiny Scanner can be used by teachers to scan some printed documents such as test papers, handouts, images or pictures. This will also be useful in scanning books to be shown in a large screen or projector.