Documentation
The Documentation will be put on the web in stages.
The documentation here is in tables. The first table looks at the Sub Menu. The other tables describes the entries of the Sub Sub Menu.
Most calculations on computers are done using binary arithmetic. The numbers used are often 8 byte in size at the most. Integer mathematical operations tend to be accurate between 1 to 4,294,967,295. Outside this range errors can manifest because of the limitations of 8 byte integers. Some computers are using 16 byte integers, but again this has limitations when numbers bigger than 1,152,921,504,606,846,975 are needed.
Floating point arithmetic runs into problems when calculating fractional numbers. For some decimal fractions there is no binary equivalent. For example "1001/5 = 200.2". On my computer using floating point arithmetic I get the answer of 200.19999999999999.
The calculator in this problem uses decimal mathematical calculations. This avoids the problems with decimal fractions with no binary equivalent. The calculations are using decimal (not binary) numbers with 100 or more digits.
Decimal arithmetic is explained here.
Calc 
Menu Level 
Why Needed 
Description 
1 Big numbers to 200 digits (90 digit number largest entry (Short cut "Ctrl+1") 
Sub  The size of number and number of decimal points is limited on a
computer. This produces inaccuracies for large number or
decimal point number calculations. There is sometimes doubt how an algebraic calculation is done in a computer calculation. 
As a number is calculated:
This is best seen in example in "1 Big numbers to 200 digits (90 digit number largest entry" table 
2 Calculator (40 Digit Accuracy for calculations) Functions
accurate to 9 sig fig (Short cut "Ctrl+2") 
Sub  The size of number and number of decimal points is limited on a
computer. This produces inaccuracies for large number or
decimal point number calculations. There is sometimes doubt how an algebraic calculation is done in a computer calculation. 

3 Calculator  Financial 40 decimal Places (Short cut "Ctrl+3") 
Sub  The size of number and number of decimal points is limited on a
computer. This produces inaccuracies for large number or
decimal point number calculations. There is sometimes doubt how an algebraic calculation is done in a computer calculation. 
This is similar to "1 Big numbers to 200 digits (90 digit
number largest entry". Here instead of been able to use just
one calculator I present two calculators. Each calculator has
a 40 digit accuracy. As a number is calculated:
This is best seen in example in "3 Calculator  Financial 40 decimal Places" 
4 Profit and Time Cost Calculator (40 Digits Accuracy) (Short cut "Ctrl+4") 
Sub  The size of number and number of decimal points is limited on a
computer. This produces inaccuracies for large number or
decimal point number calculations. When working out profit and loss it can be very difficult to do a spreadsheet with cells that relate to values present in other cells. There is sometimes doubt how an algebraic calculation is done in a computer calculation. 
This presents:
The screen is 800x620. The screen has an up button which moves it up by 100 pixels to help users with smaller screens. This is best seen in example in "4 Profit and Time Cost Calculator (40 Digits Accuracy)" 
5 Hex and Binary to Decimal (Short cut "Ctrl+5") 
Sub  There is sometimes a need to convert to Hhex and Binary when
examining computer files. 
Various means to convert to Hex and Binary numbers and back. This is best seen in example in "5 Hex and Binary to Decimal " 
Gcode  Sub 

menu display  1 Big numbers to 200 digits (90 digit number largest entry 
screen display  
clipboard entry 
Calculation = 111122333243434545454656565576576767/313+2x3.56789/7 Albrebra = (A/B)+(CxD/E),Number of entries = 5, Result of 100 digit calculation = 355023428892762126053215864461907.62323100867183934276586033774532177088087631218621633957097215883158375171154723870378822455499771 Result of 8 byte calculation = 355023428892762130000000000000000, Scientific notation Result of 8 byte calculation = 3.550234288927621e+032 Difference between 100 Digit calculation and 8 byte calculation = 3946784135538092.37676899132816065723413966225467822911912368781378366042902784116841624828845276129621177544500229 Error in calculation as a result of division occurred = .0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000002 
menu display  2 Calculator (40 Digit Accuracy for calculations) Functions accurate to 9 sig fig 
screen display  
clipboard entries from calculators 
Calculation = 1+1x2x2+2x2+(2x2x2+2)/3 Albrebra = A+(BxCxD)+(ExF)+(((GxHxI)+J)/K),Number of entries = 11, Result of 40 digit calculation = 12.33333333333333333333333333333333333333 Scientific notation Result of 40 digit calculation = 1.233333333333333e+001 Calculation = 56x90+3 Albrebra = (AxB)+C,Number of entries = 3, Result of 40 digit calculation = 5043 Scientific notation Result of 40 digit calculation = 5.043e+003 Calculation = 456/7 Albrebra = A/B,Number of entries = 2, Result of 40 digit calculation = 65.14285714285714285714285714285714285714 Scientific notation Result of 40 digit calculation = 6.514285714285714e+001 
menu display  3 Calculator  Financial 40 decimal Places 
screen display  
clipboard entry for two calculations shown in screen display 
Calculation = 1+1x2x2+2x2+(2x2x2+2)/3 Albrebra = A+(BxCxD)+(ExF)+(((GxHxI)+J)/K),Number of entries = 11, Result of 40 digit calculation = 10.33333333333333333333333333333333333333 Result of 8 byte calculation = 10.333333333333334, Scientific notation Result of 8 byte calculation = 1.033333333333333e+001 Difference between 40 Digit calculation and 8 byte calculation = .00000000000000066666666666666666666667 Error in calculation as a result of division occurred = .0000000000000000000000000000000000000008 Calculation = 1111223332434545454656565576576767/313+2x3.56789/7 Albrebra = (A/B)+(CxD/E),Number of entries = 5, Result of 40 digit calculation = 3550234288928260238519378838904.42834282975810132359653126426289365586 Result of 8 byte calculation = 3550234288928260300000000000000, Scientific notation Result of 8 byte calculation = 3.55023428892826e+030 Difference between 40 Digit calculation and 8 byte calculation = 61480621161095.57165717024189867640346873573710634414 Error in calculation as a result of division occurred = .0000000000000000000000000000000000000002 
menu display  4 Profit and Time Cost Calculator (40 Digits Accuracy) 
screen display  
clipboard entry for five calculations shown in screen display 
Input Oh Table 1 Tot = Oh+C+Dc+Tc P = SbTot P% = Px100/Tot Pno = SbC Pno% = (Pnox100)/C Sa = (Sbx(100+St))/100 C, Oh, St, Dc, Tc, Sb, Sa, Tot, P, P%, Pno, Pno% 1, 1, 1, 1, 1, 1, 1.01, 4, 3, 75, 0, 0 Input Oh Table 2 Tot = Oh+C+Dc+Tc P = SbTot P% = Px100/Tot Pno = SbC Pno% = (Pnox100)/C Sa = (Sbx(100+St))/100 C, Oh, St, Dc, Tc, Sb, Sa, Tot, P, P%, Pno, Pno% 2, 1, 2, 2, 2, 2, 2.04, 7, 5, 71.42857142857142857142857142857142857142, 0, 0 Input Oh Table 3 Tot = Oh+C+Dc+Tc P = SbTot P% = Px100/Tot Pno = SbC Pno% = (Pnox100)/C Sa = (Sbx(100+St))/100 C, Oh, St, Dc, Tc, Sb, Sa, Tot, P, P%, Pno, Pno% 1, 4, 20, 1, 1, 20, 24, 7, 13, 185.71428571428571428571428571428571428571, 19, 1900 Input Ch TotC = ChxNh Tic = Ni/TotC Tis = (Nhx60x60)/Ni Ch, Nh, TotC, Ni, Tic, Tis 1, 1, 1, 1, 1, 3600 Input Ch TotC = ChxNh Tic = Ni/TotC Tis = (Nhx60x60)/Ni Ch, Nh, TotC, Ni, Tic, Tis 4, 1, 4, 20, 5, 180 
menu display  5 Hex and Binary to Decimal 
screen display  
clipboard entry for eight calculations shown in screen display 
12 2 12 C 1 AA 2 170 3 AB 2 341 3 155 3 2 1 HEX to Character String 45 E 1 Chararacter String to Hex this is a test 14 74 68 69 73 20 69 73 20 61 20 74 65 73 74 Number Bytes 14 7468697320697320612074657374 Number Chars in string 28 Double (64 bits) unsigned integer Number of Bytes 8 Number Conversion Hex Entry FF 2 Hex Convert FF00000000000000 16 Decimal 255 3 Hex Conversion Decimal Entry 345 3 HEX from Result 5901000000000000 16 check 345 Binary Number 111111 6 Hex 3F Decimal 63 2 Decimal 56 2 Hex 38 2 Binary Number 111000 6 