Comparison

Smart Adding Machine vs HP15C

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Smart Adding Machine

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This app has a numeric keyboard. It may not always be visible. If it is not visible, pressing the input button that has the text 'Insert an Amount or ...', will cause one to appear. If you want to hide it, select the button on the left titled 'Hide KB'. The Adding Machine contains a visual tape with two columns of numbers. The left is the amount you keyed. The right column has in a '1' which is the count. The system puts in a '1' for you. As you add items, the tape grows. The last item is always followed by an empty item colored red. This color red is important because it indicates where your next entry will be placed!!! After entering a number, press the 'Save' button. If this is your first entry, two items will appear on the tape. The first one will contain the number you keyed. The second will be red with the amount showing: 0.00 and a count showing 1. This pattern will continue as you add items On the left side of the screen are 11 buttons in a column. The first six are for moving the red color - but not its contents. This allows for the correction of errors. The first two are: first - go to tape start & second to tape end (red item). The second two go up one item and down one item on the tape. The last of the group switch between amount & count - usually used to change the count from 1. There a 4 named buttons the effect the tape: Clear, Insert (an empty row where the red is, Delete(the row that a red item) and Hide KB. The keyboard has no minus sign. There is a slider button that can be used to cause an number to be negative. It is red for emphasis At least 50 items can be entered. The tape can be scrolled by using your finger to see the entire tape. At the very top of the screen is a 'Help' chevron that switches to a page of help text.

About

HP15C

Relive the classic computing experience with a vintage scientific calculator. This app emulates a beloved 90s model, offering a nostalgic and functional tool for calculations.

Highlights
  • Vintage scientific calculator emulation
  • Classic 90s design
  • Functional for scientific calculations
  • Nostalgic user experience
Features
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Vintage classic scientific calculator. The 90s are back baby! A really special person asked me to build this calculator as it was his favorite calculator, here it goes my dear. privacy policy: https://fermave.com Terms of service: https://www.apple.com/legal/internet-services/itunes/dev/stdeula

Screenshots

Smart Adding Machine4 screens
HP15C4 screens

Verdict

The call

The clearest difference is update cadence: Smart Adding Machine at every 3 weeks against HP15C's every 6 months. Smart Adding Machine also leads on price ($3.99 vs $4.99). HP15C's advantage is iOS requirement (15.6 vs 17.0). On ads, in-app purchases and device support there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Smart Adding Machine costs $3.99 and HP15C $4.99 up front. Neither carries in-app purchases, so what you see is what you pay.

UpkeepUpdate frequency

Smart Adding Machine ships an update every 3 weeks, HP15C every 6 months. The most recent releases landed on October 11, 2026 and October 13, 2026 respectively.

Scorecard3 real differences · 7 level
Smart Adding Machine versus HP15C: the parameters behind the verdict, then further details
ParameterSmart Adding MachineHP15C
Price$3.99 — better$4.99
Rating—2.7 (3 ratings) — better
Positive reviews—33.3% of reviews
Number of ratings—3 — better
Update frequencyEvery 3 weeks — betterEvery 6 months
AdsNoNo
In-app purchasesNoNo
Monetization—Paid
DevicesiPhone, iPad, MaciPhone, iPad, iPod
Requires iOS17.015.6 — better
Further details — not scored
Size0 MB24 MB
Age rating4+4+
DeveloperHarry DetrickFERMAVE

In-app purchases

None

Smart Adding Machine

No in-app purchases

None

HP15C

No in-app purchases

Questions

Is Smart Adding Machine free?
Smart Adding Machine costs $3.99, with no in-app purchases.
Is HP15C free?
HP15C costs $4.99, with no in-app purchases.
Do Smart Adding Machine or HP15C have ads?
Neither Smart Adding Machine nor HP15C shows ads.
Which is updated more often, Smart Adding Machine or HP15C?
Smart Adding Machine ships an update every 3 weeks, and HP15C every 6 months. Most recently, Smart Adding Machine was updated on October 11, 2026 and HP15C on October 13, 2026.

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