Hello again. Here's another article that I will broaden the ability to add quick.
It also illustrates a fundamental principle of mental arithmetic, that is, to simplify the problem by dividing it into smaller, more manageable parts easier. This is the key to almost all the methods you'll learn. To paraphrase an old saying, there are three components to success, simplify, simplify, simplify.A). The easiest problem of two-digit sum is not required to carry any number, when the sum of the first digit of 9 or less, and the sum of the last digit of 9 or less. For example:47 + 32 (30 + 2)To solve 47 + 32, first add 30, then add 2. After addition of 30, you have the simpler problem 77 + 2, which equals 79. Illustrated as follows:47 + 32 = 77 + 2 = 79
(First add 30) (then add 2)
The above scheme is simply a way of representing the people the mental process involved in arriving at an answer by this method.Now we will try to bring a calculation that requires a number:67 + 28 (20 + 8)Sum from left to right, you can simplify the problem by adding 67 + 20 = 87, then 87 + 8 = 95.67 + 28 = 87 + 8 = 95(First add 20) (then add 8)Now try one by yourself, mentally calculating from left to right, then check to see how we did it:84 + 57 (50 + 7)How was that? You've added 84 + 50 = 134 and added 134 + 7 = 141.84 + 57 = 134 + 7 = 141(First add 50) (then add 7)Try another problem for practice, once again the computer in your mind first, then check how you did:68 + 45 (40 + 5)You should have added 68 + 40 = 108, and 108 + 5 = 113, the final answer. ! This time it is easier
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