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（17） A Leg Walking Right Here are some signs + - x, the signs are very different. They mean very different things. When you see them, you know what to do. This sign + means that you will add some numerals. This sign-means that you will take one numeral away from another. You will subtract（减去）. What will you do when you see x and ? Our signs are easy to read. They are easy signs to remember. Look at these two signs .The ancient Egyptians used these signs. A picture of a leg walking to the left told them to add some numerals. A picture of a leg walking to the right told them to subtract. In the 1500s people used this printed（印刷的） signto add numerals. After a while the sign began to look like this .Later, the sign became +. How much is 22? 1. What do you do when you see this sign +? A. Walk away B. Write a numeral C. Read a sign D. Add 2. The word in the story that means to take one numeral away from another is _____. 3. The story says, Our signs are easy to read. They are easy signs to remember. The word they means ______. 4. Which of the following does this story lead to believe? A. Egyptians could not add numerals together B. All Egyptians had two left legs. C. Our signs are not hard to understand | 
