69tribe
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Join date: 2008-08-05
 |  Subject: Math IQ (chinese)  Thu Oct 23, 2008 5:47 pm | |
| 数学IQ 请问1+2+3+4+......+99+100=多少？ 觉的很浪费时间在算。那怎么算才能快速算到答案呢？ 教你一个笨蛋算法 1+2+3+4+5+6+7+8+9+10=55 11+12+13+14+15+16+17+18+19+20=155 21+22+23+24+25+26+27+28+29+30=255 这里可以得出以下 1+2+3+4……+100=55+155+255+355+455+555+655+755+855+955 55+155+255+355+455+555+655+755+855+955睇到这行不要晕，算下有十个55=550。以下就系100+……900等于 1加到9 =45加上00就是4500+550=5050咯 _________________ I've had an illustrious career on this magnificent forum. |
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Death
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Join date: 2008-08-05
Location: Milky Way Galaxy
| | Subject: Re: Math IQ (chinese) Thu Oct 23, 2008 7:32 pm | |
| | Quote: | | Another famous story, and one that has evolved in the telling, has it that in primary school his teacher, J.G. Büttner, tried to occupy pupils by making them add a list of integers. The young Gauss reputedly produced the correct answer within seconds, to the astonishment of his teacher and his assistant Martin Bartels. Gauss's presumed method, which supposes the list of numbers was from 1 to 100, was to realise that pairwise addition of terms from opposite ends of the list yielded identical intermediate sums: 1 + 100 = 101, 2 + 99 = 101, 3 + 98 = 101, and so on, for a total sum of 50 × 101 = 5050 (see arithmetic series and summation).[5] However whilst the method works, the incident itself is probably apocryphal; some, such as Joseph Rotman in his book A first course in Abstract Algebra, question whether it ever happened. |
Something like this?
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