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Curious and Useful Math A math student's companion consisting of the most useful rules and memoranda, collected from some of the best texts of the day, and practically tested by many years' experi...

Squaring Tricks Multiply the ones digit by 2. This becomes your second digit. Retain the tens digit (i.e., 1) and append the above results. Example: \(17^{2}\) \(7^{2}=49\). The 9 is your last dig...

A Possible Trick for Calculating Percentages Sometimes a difficult percentage calculation can be made easy simply by swapping the two terms. For example: In your head, you may find it difficult to com...