Lithograph from 1828, by Siegfried Detlev Bendixen, showing a portrait of the German mathematician Carl Friedrich Gauss at the age of 50. Source: http://commons.wikimedia.org/wiki/File:Bendixen_-_Carl_Friedrich_Gau ß,_1828.jpg.From en.wikipedia.org/wiki/Carl_Friedrich_Gauss: “Johann Carl Friedrich Gauss (/ɡaʊs/; German: Gauß, pronounced [ɡaʊs]; Latin: Carolus Fridericus Gauss) (30 April 1777 – 23 February 1855) was a German mathematician who contributed significantly to many fields, including number theory, algebra, statistics, analysis, differential geometry, geodesy, geophysics, mechanics, electrostatics, astronomy, matrix theory, and optics.Sometimes referred to as the Princeps mathematicorum (Latin, "the foremost of mathematicians") and "greatest mathematician since antiquity", Gauss had an exceptional influence in many fields of mathematics and science and is ranked as one of history's most influential mathematicians.”Yes, he was all that and a lot more. But my favorite story is from his childhood. It is said one day his math teacher needed to do some work instead of teaching, so at the beginning of the lesson he told the pupils to add up the numbers from 1 to 100. They starting working and the teacher started doing whatever it was he needed to do. But just a few minutes later, young Karl raised his hand and said the numbers added up to 5050. The teacher just shook his head and told Karl not to fib.Closer to an hour later other pupils started raising their hands and they also said the result was 5050. The teacher then asked Karl how he could calculate the result so quickly. Karl said that 1+100=101, 2+99=101,3+98=101,...,50+51=101. There were fifty such pairs that added up to 101 each. Therefore, the sum of the numbers from 1 to 100 equals 50 times 101, and that is 5050. Duh!Whether the story is true or not, that is the basis of Gauss’ algorithm for adding any sequence of numbers starting anywhere and ending anywhere else. And it shows Gauss would make an amazing computer programmer because this type of problem solving is the heart of computer programming.
卡爾弗里德里希高斯
algebra、analysis、astronomy、blur、curve、differential、distribution、electrostatics、etc、Friedrich、Gauss、Gaussian、Gauß、geodesy、geometry、geophysics、German、Karl、mathematician、mathematics、matrix theory、mechanics、noise、number theory、optics、Princeps mathematicorum、Semi-Realistic People、statistics
代數、分析、天文學、模糊、曲線、微分、分配、靜電學、等等、弗里德里希、高斯、高斯、高斯、大地測量、幾何、地球物理、德語、卡爾、數學家、數學、矩陣理論、機械學、噪聲、數論、光學、高等數學、半現實的人、統計
資料來源：openclipart ( https://openclipart.org/ )

Redhead Mermaid With Freckles.
紅頭髮美人魚與雀斑
Cartoon、Comic、Female、Fictional、Fish、Freckles、Girl、Half、Hybrid、Marine、Mermaid、Mythical、Mythological、Non-Human Beings、Ocean、Redhead、remix+253291、Sea、Swim、Water、Woman
動畫片、滑稽、女、虛構、魚、雀斑、女孩、半、混合動力、海洋、美人魚、神話、神話、非人類、海洋、紅發、混音+ 253291、海、游泳、水、女人
資料來源：openclipart ( https://openclipart.org/ )

header for ribbons and butterflies
頭
border、Decorative elements、header、ribbons
邊界、裝飾元素、頭、緞帶
資料來源：openclipart ( https://openclipart.org/ )

Clipped from a drawing (by heblo) on Pixabay and vectorized.
跳舞夫婦16
couple、dance、dancer、dancing、performance、silhouette
一對、舞蹈、舞蹈家、跳舞、性能、輪廓
資料來源：openclipart ( https://openclipart.org/ )

Adapted from an image uploaded towww.publicdomainpictures.net by user X posid
睡覺的電腦用戶（＃1）
cartoon、chair、Comic characters、computer、desk、desktop、keyboard、male、man、PC、personal、sleep、sleeping、snore、snoring、tired、user
動畫片、椅子、漫畫人物、電腦、台、桌面、鍵盤、男、人、個人計算機、個人、睡覺、睡眠、鼾聲、打鼾、累、用戶
資料來源：openclipart ( https://openclipart.org/ )

Wooden matches with "strike anywhere" tip
廚房比賽（在任何地方打擊）
burn、fire、kitchen、match、safety、strike anywhere、wood
燒傷、火、廚房、比賽、安全、罷工、木
資料來源：openclipart ( https://openclipart.org/ )

No vaping sign.
Rones沒有vaping標誌
sign、smoke、vaping
標誌、抽煙、vaping
資料來源：openclipart ( https://openclipart.org/ )

Vegetable bowl. Download more free cliparts at www.cg4share.com.
蔬菜碗
bowl、carrot、farm、farmer、food、garden、home、kitchen、vegetable
碗、胡蘿蔔、農場、農民、餐飲、花園、家、廚房、蔬菜
資料來源：openclipart ( https://openclipart.org/ )

This image was adapted from a picture posted to publicdomainq.net. All of the images on these sites are in the public domain i.e. CC0. This site is only in Japanese but can be easily navigated with Google Translate.
商人 - 大喊
call、Comic characters、cute people、happy、hey、male、Male Characters、man、Manga、office、publicdomainq.net、shout、suit、tie
呼叫、漫畫人物、可愛的人、快樂、嘿、男、男性角色、人、漫畫、辦公室、public domain Q.net、喊、適合、貼
資料來源：openclipart ( https://openclipart.org/ )

Remix of the Nursing Career sign/poster. I forgot to add the word "Healing", in the original. The nurse is remix from a upload by cactus cowboy.
護理職業2
cactus+cowboy、career、health+care、healthcare、hospital、medical、Nurse、nursing、remix+236701、remix+287140、remix+291970、remix+294718、request+236701、request+completed、request+filled
仙人掌+牛仔、事業、健康護理+、衛生保健、醫院、醫、護士、看護、混音+ 236701、混音+ 287140、混音+ 291970、混音+ 294718、請求+ 236701、請求完成+、請求+填充
資料來源：openclipart ( https://openclipart.org/ )