Math CentralQuandaries & Queries


Question from Chew, a student:

What is 777777 times 111111 without using a calculator?


It is hard for me to figure out the purpose of this question -- it looks to be a pattern-recognition question, but I fail to see much of a pattern. Notice that your problem is simply to first square 111111 and then multiply it by 7. Of course 11...12 has a nice pattern -- for you to discover it you should compute 112, 1112, 11112, and so on. For your problem you should multiply each of these by 7; do you see an interesting pattern? I do not.


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