Editing Sinclair Scientific (section)

===Calculations using the Sinclair Scientific===

The Sinclair used a slightly altered [[Reverse Polish notation|Reverse Polish Notation]] method; lacking an enter key, the operation keys enter a number into the appropriate register and the calculation is performed.  For example, (1+2) × 3 could be calculated as: {{kbd|C 1 + 2 + 3 ×}} to give the result of {{samp|9.0000 00}} ({{val|9.0000|e=0}}, or 9).  The {{key top|C}} key performs a clear; pressing it sets the calculator to a state with zero in the internal registers.  Pressing "C" followed by number keys then {{key top|+}} effectively adds the number entered to the zero and stores it internally to be worked on in subsequent calculations.  If the {{key top|&minus;}} key is pressed instead, the number is subtracted from zero, effectively entering a negative number.<ref name="manual">{{cite web|title=Sinclair Scientific Operating Instructions|url=http://phils.bitboxes.co.uk/scan_and_ocr/manuals/sinclair_scientific/|url-status=dead|archive-url=https://archive.today/20140821181554/http://phils.bitboxes.co.uk/scan_and_ocr/manuals/sinclair_scientific/|archive-date=21 August 2014|access-date=20 August 2014|publisher=Sinclair Research}}</ref>

All numbers are entered in scientific notation.  After entering the mantissa part of the number, the "E" exponent key is pressed prior to entering the integer exponent of the number.  The task of ordering the operations is placed on the user, and there are no bracket keys.  The display shows only five digits, but six digits can be entered.<ref name="manual"/>  As an example 12.3×(&minus;123.4+123.456) could be entered as {{kbd|C 1 2 3 4 E 2 - 1 2 3 4 5 6 E 2 + 1 2 3 E 1 ×}} for a displayed result of {{samp|6.8880 -01}} (representing {{val|6.8880|e=-1}}, or 0.68880).

Four constants are printed on the calculator case for easy reference.  For converting to and from base 10 logarithms and natural logarithms, the natural logarithm of 10 (2.30259) and e (2.71828) are printed on the case. {{Pi}} (3.14159) and 57.2958 (180 / {{Pi}}) are also on the case for trigonometry calculations.  There was not enough internal memory to store these constants internally.  Angles are computed using radians; degree values must be converted to radians by dividing by 57.2958.  As an example, to calculate 25 sin (600×0.05°) one would enter {{kbd|C 6 E 2 + 0 0 5 × 5 7 2 9 5 8 E 1 ÷ ▲ + 2 5 E 1 ×}} to get a result of {{samp|1.2500 01}} (representing 12.5 which is equal to 25 sin(30°) ).  Sine is selected with the combination of the {{key top|▲}} key followed by the {{key top|+}} key.  The {{key top|▼}} (down) and {{key top|▲}} (up) arrow keys are function select keys.  The four operation keys ({{key top|&minus;}}, {{key top|+}}, {{key top|÷}} and {{key top|×}}) all have two other functions, activated by using one of the arrow keys.  The functions available are sine, arcsine, cosine, arccosine, tangent, arctangent, logarithm and antilogarithm.