เทคนิคการคิดลัดหาคำตอบได้อย่างรวดเร็ว
ให้หาตัวกลางของจำนวนที่บวกกันนั้น คูณกับจำนวนที่ให้บวกกันทั้งหมด
ตัวอย่าง เช่น
97 + 98 + 99 + 100 + 101 = .............................
สังเกตพบว่่าจำนวนที่ให้บวกกันนั้นทั้งหมดมี 5 จำนวน และตัวกลางของจำนวนเหล่านี้คือ 99
ให้เอา 5 99 = 495
ดังนั้น 97 + 98 + 99 + 100 + 101 = 495
ลองคิดดูเล่นๆ ค่ะ
1. 15 + 16 + 17 = .................. (48)
2. 125 + 126 + 127 + 128 129 = ................... (635)
3. 63 + 64 + 65 + 66 + 67 + 68 + 69 + 70 + 71 = ................... (603)
ที่มาhttp://www.thaigoodview.com/library/teachershow/lopburi/benja_j/easy_math/sec01p04.html
The society in Spain is traditionally for centuries, with a culture strongly skewed towards its humanistic components. In Spain, culture seems to be synonymous with literature, painting, music … Many of our enlightened people make no bones whatsoever to confess openly their deep ignorance of the basic elements of mathematics and science and even seem to boast Although without any. The pages of most of our newspapers have not yet realized that science, particularly mathematics, and today constitute one of the pillars of human culture. Furthermore, it seems clear that, as Whitehead says, “If civilization continues to advance in the next two thousand years, the new dominant human thought is the domain of intellection math.”
It would be desirable that all members of the scientific mathematical community and we strive very hard to make it clear to society for the influential presence of mathematics and science in culture. A society with a clear understanding of what science is for development will be collectively more sensitive to the problems of education of the youngest in this sense represents.
In the international mathematical community recently has been paying great attention to the appropriate resources to achieve open the eyes of broad sectors of society to the benefit of all the orders that can bring a culture where, in the right way, science and math.