Retro Review: Radio Shack EC-21 (Blackjack Calculator)

Retro Review: Radio Shack EC-21 (Blackjack Calculator) 

Welcome to my birthday blog.  44 years today (March 14, 1977).  

Quick Facts:

Models:  EC-21

Company:  Radio Shack

First Manufactured: 1978

Memory Register:  1 independent memory

Battery:  3 AAA

The Calculator and The Game

The Radio Shack EC-21 is a dual-purpose calculator:  a 10-digit calculator and full blackjack game.

The Calculator

The calculator is a 10 digit, four function calculator with something extra:  a parenthesis [ ( ) ] key.   The parenthesis key allows the user to put certain calculations in higher priority.   The calculator operates in chain mode, the order of operations is not taken into consideration.

Example:  

2 x (3 + 9) = 24

Keystrokes:  2 [ x ] [ ( ) ] 3 [ + ] 9 [ ( ) ] [ = ]

The calculator has a square root function, but it does not have a memory register.

The Game:  Blackjack

In GAME mode, the EC-21 is a one player blackjack game.  It is you against the house.  The house stands on 17 - 21.   

Enter a bet and press the [ √ ] (BET) key.   You are not limited in bankroll.  Once you place the bet, the screen shows all zeroes as the calculator shuffles a deck of 52 playing cards.  Kings, queens, jacks, and tens are shown on the display as an F (face card).  Aces, shown by an A, count as either 1 or 11.  The ace is counted to the player's best benefit.  

If you get a blackjack (Ace and a Face card) you automatically win, the payout is 3:2.  

The game keys are:

[ = ] (HIT): Hit: The player takes a hit.  Be careful, going over 21 will cause you to bust and lose the game.

[ - ] (INS):  Insurance:  If the Dealer's up card is an Ace, you can take insurance, which is half of your bet.  If you take Insurance and the Dealer has a blackjack (Ace and a Face card), you lose only half your bet.

[ + ] (STD):  Stand.   Press this key when you decide to take no more cards.

[ ÷ ] (SPL):  Split.  If you are dealt a pair, you can split your cards into two hands.  If you split aces, you only get one more card per ace.   In this case, any 21 pays off at 1:1.  

[ × ] (DBL):  Double Down.  If you have strong starting hand, such as a 10 or 11 against a Dealer's favorable up card, you can double your bet for one more card.  

After each hand, press the total key ( [ ( ) ] (TOL) ) to check your earnings.  

Keyboard

The keyboard has a solid feel.  However, the keys require a firm press to register.  I have the best luck of holding the calculator in my hand.  In my experience, laying the keyboard down flat did not allow me to register all the keys, particular the zero key.  If wish the keys were not hard to press.  It may be the luck of the draw when I made the purchase. 

I love the colors:  green for the number keys, red of the clear keys, blue for the function keys.  

Verdict

The calculator is stored in a beautiful leather case, and the green display is awesome.  I also like the two-in-one calculator/game.  I wish the keyboard is better, but buying it is not expensive, and I am happy to have this in my collection.  

Source:

Flow Simulation, Ltd.  "Radio Shack EC-21 (Blackjack 21)"  Retrieved January 22, 2021.  https://americanhistory.si.edu/collections/search/object/nmah_334462 

National Museum of American History Behring Center.  "Radio Shack EC-21 Handheld Electronic Calculator, Blackjack"  Washington D.C. Retrieved January 23, 2021.  https://americanhistory.si.edu/collections/search/object/nmah_334462

Eddie

All original content copyright, © 2011-2021.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author. 

Blackjack: Approximate Chance of Busting (HP 48G)

Blackjack:  Approximate Chance of Busting

In standard game of Blackjack, the main objective is beat the dealer’s hand.  Usually this occurs if your hand has a better total (no more than 21) than the dealer’s hand.  At any time if the total of your hand exceeds 21, you bust, or automatically lose. 

As your score increases, the number of cards that can cause you to bust increase.

If your score is 11 or less, you cannot bust on the next card.  Even if you get an Ace, Aces are 1 or 11, and are always used to your best benefit.

If your score is 12, if the next card is any face card or ten, you bust.  There are 16 face cards and tens in a standard deck of 52 playing cards.  The face cards are Jacks, Queens, and Kings.  In Blackjack, face cards count as 10 points.  Below is a table of score and bust cards.

Your Score	Bust Cards	Number of Bust Cards per Deck of 52 Playing Cards
12	Face Cards, Tens	16
13	Face Cards, Tens, Nines	20
14	Face Cards, Tens, Nines, Eights	24
15	Face Cards, Tens, Nines, Eights, Sevens	28
16	Face Cards, Tens, Nines, Eights, Sevens, Sixes	32

If your score is 17 and above, basic Blackjack strategies dictate that you stand (draw no more cards).

Approximating the Odds of Busting

To calculate the odds of busting, we have to determine two things:  (I) the number of bust cards that remain, and (II) the number of cards remaining to be dealt.

The number of bust cards that remain are:

d * (4*t – 32) – b  

Where:

d = the number of decks in play.  Decks are assumed to standard decks of 52 playing cards, without jokers.

t = your score.  For our purposes, 12 ≤ t ≤ 16.  Outside this range, this formula does not make sense.

b = the number of bust cards used.  Unless you are counting cards, this is an estimate number. 

The number of cards remaining to be dealt:

52*d – n

Where:

d = the number of decks in play (same as above)

n = number of cards that have been played

The odds of busting on the next card is:

OB = (d * (4*t – 32) – b )/( 52*d – n)

Let’s calculate some approximate odds of busting. 

Scenario #1:  The table is just you and the dealer.  It is the first hand the session and 6 decks are used.  On the first hand both you and the dealer have been dealt a face card. 

Variables: d = 6, b = 2 (two bust cards used), n = 4 cards dealt (one card has an unknown value)

Score (t)	Chance of Busting
12	30.5195 (%)
13	38.3117 (%)
14	46.1039 (%)
15	53.8961 (%)
16	61.6883 (%)

Scenario #2:  Now the table are six players and the dealer.  Five hands have been dealt and now we are on the sixth hand.  There 6 decks being used and let’s assume that 88 cards have been used, 28 bust card used. 

Variables:  d = 6, b = 28, n = 88

Score (t)	Chance of Busting
12	30.3571 (%)
13	41.0714 (%)
14	51.7857 (%)
15	62.5000 (%)
16	73.2143 (%)

Scenario #3:  Now the table are six players and the dealer.  Same as above, let’s time assume that 40 bust cards have been used, a lot of high cards have been dealt.

Variables:  d = 6, b = 40, n = 88

Score (t)	Chance of Busting
12	25.0000 (%)
13	35.7143 (%)
14	46.4286 (%)
15	57.1429 (%)
16	67.8571 (%)

A quick observation is that the more bust cards that have been used, the lower the chances of busting later on.  Obviously, having a score of 15 or 16 is not a desirable score since the dealer stands on 17 and above.  15 and 16 are desirable if only a dealer has a weak up card (3-6) and the dealer’s chances of busting is high (assuming the hidden card is a 9, 10, or face card).

The approximations have been calculated using an HP 48GX:

HP 48G Program OBUST:

Stack:  t, d, b, n

≪ → T D B N

≪ 4 T * 32 – D * B – 52 D * N - / →NUM 100 * ≫

≫

And no, I don’t count cards during a blackjack game.  In a real life game, I try to apply basic strategy and hope for the best. 

Until next time,

Eddie

This blog is property of Edward Shore. 2016