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                | Number Magic |  | 
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	 	| Question : |  
	 		| What are Signed Numbers ? |  
	 	| Answer :
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	 		| Signed numbers are actually a book keeping concept which were used in book-keeping by the ancient Greeks, Chinese and 
			Hindus more than 2,000 years ago. |  
	 		| Merchants wrote positive numbers in black and negative numbers in red in their account 
			books. Many banks still use red to show negative credit. |  |