Scientific Calculator “RETRO”, emulates the operation of a calculator of the year 1982 with real scientific notation, allows 12 digit mantissa inputs + exponents up to ± 99
Operations:

• 4 basic calculations, constants for +,-, x, /, and 18 parenthesis in one level calculations
• This calculator evaluates automatically the precedence of the operations and runs them calculations in the sequence appropriate thus determined.
• Help Key [?]
• Double display, one for entries / results other that indicates that memories of constants mem-k1 to k6 are active

Built-in functions:

• Trigonometric/inverse trigonometric (with angle in degrees, radians or gradients)

• Hyperbolic functions

• Logarithmic/exponential functions

• Reciprocals

• Factorials

• x², x³, x^y powers

• Square and x^1/y roots

• Conversion of co-ordinate system (Rectangular->Polar, Polar->Rectangular)

• Percentages.

• RND key for Random number generation with Botton-Top user control.

• Sexagesimal <-> Decimal degrees conversion and vice versa

• Decimal <-> Engineering notation conversion and vice versa

• Degrees <-> Radians conversion and vice versa

• Celsius <-> Fahrenheit degree conversion and vice versa

• K Constant operatión xx, //, --, ++

• Exponent/Pi entry key
  Memory:

• 1 independent memory

• 6 constant memories K1 to K6 + 2 constant memories of double function R-b and R-t.
  Even when power is off, the contents is held in independent memory and constant memory registers, are not lost.

• M+ Adds the displayed number to the contents of the independent memory, and obtains answer in 4 basic calculations, x^y, x^1/y and automatically adds it to the contents of the memory.

• M- Subtracts the displayed number from the contents of the independent memory, and obtains answer in 4 basic calculations x^y, x^1/y and automatically subtracts it from the contents of the memory when pressed after the INV key.

E.g.
Sequence of operations:
0 [Min] Display=0 -> MR=0
24 [M+] Display=24 -> MR=24
14 [M-] Display=14 -> MR=10
5x6 [M+] Display=30 -> MR=40
2 X^y 3 [M-] Display=8 -> MR=32
16 X^1/y 4 [M+] Display=2 -> MR=34

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Percentages:
15% add-on of 2500
2500 [x] 15 [INV][%] -->> 375 [+] -->> 2875

25% discount of 3500
3500 [x] 25 [INV][%] -->> 875 [-] -->> 2625
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For the youngest.
Fill in a lotto ticket with random numbers genetared by the calculator:
As you know a lotto ticket has 49 boxes so we have to generate random numbers between 1 to 49
First we introduce the lowest value “1” in the reserved memory for this purpose mem R-b (Botton)
1[Kin] [mem R-b]
Followed by the highest number “49” in the memory reserved for this purpose mem R-t (Top)
49 [Kin] [mem R-t]
Each time we press the key [RND] the calculator will generate one random number between 1 and 49
[RND][RND][RND][RND][RND][RND] -->> 39, 22, 31, 46, 8, 20
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Entry/basic functions: 12 digit mantissa, or 12 digit mantissa plus 2 digit exponent up to 10±99.