Secrets of Mental Math Quotes

“probably heard that math is the language of science, or the language of Nature is mathematics. Well, it’s true. The more we understand the universe, the more we discover its mathematical connections. Flowers have spirals that line up with a special sequence of numbers (called Fibonacci numbers) that you can understand and generate yourself. Seashells form in perfect mathematical curves (logarithmic spirals) that come from a chemical balance. Star clusters tug on”
― Arthur Benjamin, Secrets of Mental Math: The Mathemagician's Guide to Lightning Calculation and Amazing Math Tricks

“Here is the rule for deciding which method to use: If a two-digit subtraction problem would require borrowing, then round the second number up (to a multiple of ten). Subtract the rounded number, then add back the difference.”
― Arthur T. Benjamin, Secrets of Mental Math: The Mathemagician's Guide to Lightning Calculation and Amazing Math Tricks

“Did you reduce and simplify the problem by adding left to right? After adding the hundreds (623 + 100 = 723), you were left with 723 + 59. Next you should have added the tens (723 + 50 = 773), simplifying the problem to 773 + 9, which you then summed to get 782. Diagrammed, the problem looks like this: When I do these problems mentally, I do not try to see the numbers in my mind—I try to hear them. I hear the problem 623 + 159 as six hundred twenty-three plus one hundred fifty-nine; by emphasizing the word hundred to myself, I know where to begin adding. Six plus one equals seven, so my next problem is seven hundred and twenty-three plus fifty-nine, and so on. When first doing these problems, practice them out loud. Reinforcing yourself verbally will help you learn the mental method much more quickly.”
― Arthur T. Benjamin, Secrets of Mental Math: The Mathemagician's Guide to Lightning Calculation and Amazing Math Tricks