**(1) **Explain your problem, don't simply post "This isn't working". What were you doing when you faced the problem? What have you tried to resolve - did you look for a solution using "Search" ? Has it happened just once or several times?

**(2)** It's also good to get feedback when a solution is found, return to the original post to explain how it was resolved so that more people can also use the results.

The base 21 idea gave me a good laugh. Thank you.

With the help of google and few ideas looking at a schedule in front of me, I decided to find out the history of paper, mathematics, electricity, computing tools, CPM, and here are the findings:

Paper:

1. Early people discovered that they could make simple drawings on the walls of caves, which was a great place for recording thoughts, but wasn’t portable.

2. About 5,000 years ago, Egyptians created "sheets" of papyrus by harvesting, peeling and slicing the plant into strips

3. 3,000 years. The person credited with inventing paper is a Chinese man named Ts’ai Lun.

4. 10th century, Arabians were substituting linen fibers for wood and bamboo, creating a finer sheet of paper

5. In 1448, Johannes Gutenberg, a German, was credited with inventing the printing press

Tools

1. The original compact calculator was the abacus, developed in China in the ninth century.

2. The young French mathematician Blaise Pascal (1623-1662) invented the first adding machine in 1642, a clever device driven by gears and capable of performing mechanical addition and subtraction.

3. The first commercially successful adding machine was developed in 1886 by William Seward Burroughs (1855-1898).

4. The "Millionaire," a machine invented by Otto Steiger in 1894, was the first adding machine also capable of direct multiplication.

5. The Atanasoff–Berry Computer (ABC) was the first electronic digital computing device.[1] Conceived in 1937, the machine was not programmable, being designed only to solve systems of linear equations.

6. The hand-held pocket calculator was invented at Texas Instruments, Incorporated (TI) in 1966 by a development team which included Jerry D. Merryman, James H. Van Tassel and Jack St. Clair Kilby

The numbers:

1. The Arabic numerals or Hindu numerals or Hindu-Arabic numerals are the ten digits (0, 1, 2, 3, 4, 5, 6, 7, 8, 9). The decimal Hindu-Arabic numeral system was invented in India around 500 AD.

2. While the word algebra comes from the Arabic language (al-jabr, Ø§Ù„Ø¬Ø¨Ø± literally, restoration) and much of its methods from Arabic/Islamic mathematics, its roots can be traced to earlier traditions, most notably ancient Indian mathematics

2. Prehistoric mathematics: The origins of mathematical thought lie in the concepts of number, magnitude, and form.[8] Modern studies of animal cognition have shown that these concepts are not unique to humans. Such concepts would have been part of everyday life in hunter-gatherer societies. That the concept of number evolved gradually over time is evident in that some languages today preserve the distinction between "one", "two", and "many", but not of numbers larger than two.[8]

The oldest known mathematical object is the Lebombo bone, discovered in the Lebombo mountains of Swaziland and dated to approximately 35,000 BC.[9] It consists of 29 distinct notches deliberately cut into a baboon’s fibula.[10] There is evidence that women used counting to keep track of their menstrual cycles; 28 to 30 scratches on bone or stone, followed by a distinctive marker.[11] Also prehistoric artifacts discovered in Africa and France, dated between 35,000 and 20,000 years old,[12] suggest early attempts to quantify time.[13]

The Ishango bone, found near the headwaters of the Nile river (northeastern Congo), may be as much as 20,000 years old and consists of a series of tally marks carved in three columns running the length of the bone. Common interpretations are that the Ishango bone shows either the earliest known demonstration of sequences of prime numbers[10] or a six month lunar calendar.[14] Predynastic Egyptians of the 5th millennium BC pictorially represented geometric designs. It has been claimed that megalithic monuments in England and Scotland, dating from the 3rd millennium BC, incorporate geometric ideas such as circles, ellipses, and Pythagorean triples in their design.[15]

4. The most ancient mathematical texts available are Plimpton 322 (Babylonian mathematics c. 1900 BC),[1] the Rhind Mathematical Papyrus (Egyptian mathematics c. 2000-1800 BC)[2] and the Moscow Mathematical Papyrus (Egyptian mathematics c. 1890 BC). All of these texts concern the so-called Pythagorean theorem, which seems to be the most ancient and widespread mathematical development after basic arithmetic and geometry.

Electricity

1. Benjamin Franklin and Electricity In June of 1752, he performed his famous kite experiment, drawing down electricity from the clouds and charging a Leyden jar from the key at the end of the string.

2. Thomas Edison’s greatest challenge was the development of a practical incandescent, electric light. Contrary to popular belief, he didn’t "invent" the lightbulb, but rather he improved upon a 50-year-old idea. In 1879, using lower current electricity, a small carbonized filament, and an improved vacuum inside the globe, he was able to produce a reliable, long-lasting source of light.

CPM

CPM was the discovery of M.R.Walker of E.I.Du Pont de Nemours & Co. and J.E.Kelly of Remington Rand, circa 1957. The computation was designed for the UNIVAC-I computer. The first test was made in 1958, when CPM was applied to the construction of a new chemical plant. In March 1959, the method was applied to a maintenance shut-down at the Du Pont works in Louisville, Kentucky. Unproductive time was reduced from 125 to 93 hours

Now we are using all of the above to save time and money on our construction projects. Now I have to say that my favorite was discovering tha the oldest known mathematical object is the "Lebombo bone".

With kind regards,

Samer