Eye chart number). The denominator indicates the distance in feet at which a person with normal vision could stand to correctly identify the same symbols identified by the person tested. For example, a visual acuity of 20/20 is considered normal. Numerous types of eye charts exist and are used in various situations. For example, the Snellen chart is designed for use at 6 meters or 20 feet, and is thus appropriate for testing distance vision. There is often also a need to test a subject's vision at near or occupational tasks (such as reading or computer use). For these situations, a Rosenbaum
Chain Letters but the existing letters could not be rearranged. They won £5 for each valid word and could make up to four plays, for a maximum length of seven letters. If the contestant either chose to stop or created an invalid word, their turn ended. A five-letter word was displayed, with a plus sign at the left end and a minus sign at the right. The host read a toss-up clue whose answer differed from the displayed word by one letter. The change that needed to be made was displayed when a contestant buzzed-in. If a letter was highlighted, it needed