Do these 3 things before closing this tab:
1Scan for outdated or missing drivers - takes under a minute2Repair Windows errors before they cause bigger problems3Fix the driver behind crashes, sound loss and screen glitchesA payment integration treated every amount as if it had two decimal places. When it received a yen payment of ¥3,400, it divided the value by 100 and stored ¥34, so the order system marked a correctly paid order as underpaid. Sergey Shinder recounts the incident in a September 29, 2026 DEV Community article; the incident details and figures below are his account, not independently verified findings.
How a correct yen payment became an underpaid order
Before the company began selling in Japan, its handler had dealt with pounds and euros. It applied the same conversion to every payment: divide the incoming amount by 100 to turn a minor-unit integer into a major-unit amount. That worked for the currencies it had handled before, but the handler ignored the currency code supplied alongside each amount.
As an Amazon Associate I earn from qualifying purchases.
In Shinder’s example, the payment provider delivered ¥3,400 as an integer amount in yen. The handler divided it by 100 and recorded ¥34. The customer’s payment was reportedly correct; it was the internally stored order value that was wrong. Fulfilment compared that value with the order total, classified the order as underpaid, and held it while customers were asked to pay again.
Recommended Free Tools
Shinder reports that 206 orders were held over 26 hours. Those figures describe this reported incident only; they are not independently audited or a measure of how often this kind of bug occurs.
#1 Best Overall
- 【Professional and Precise Detection】Multiple detection modes can be used individually or simultaneously. When the cash is fake/broken/non-magnetic/normal size banknotes, the LCD display of Aneken money counter will show red error code and sound an alarm.
- 【Multiple Functions】Count-Count the number of bills. Add-Multiple bill counting batches can be added together. Batch-The money counter stops each time the set number of bills to be counted is reached. The bill counter can also be selected in manual or automatic mode.
- 【Count Value】The money counting machine can identify banknote denominations by manually setting the "Value". In conjunction with the “Add” mode, the sum of the values of bills can be calculated. PLEASE NOTE: The bill counter does not automatically recognize the denomination of the bills.
- 【Reliable & Efficient】The high efficiency motor of the bill counter can count 1000 bills per minute. The noise level is less than 60 decibels.PLEASE NOTE: This product operates on 110V ONLY.
- 【Security Protection】For your privacy and security, there is no information about the cash counting machine on the outer box, ensuring the safety of your cash business. We provide lifetime technical support for the cash counting machine. And will reply and provide the best service within 12 hours.
Why dividing every payment by 100 fails
A numeric payment amount has no safe, universal interpretation on its own. Its currency determines how the value relates to the amount a customer sees. Some currencies use two decimal places, while others use none or three. A conversion rule that assumes two decimal places can therefore misread a valid payment by a factor of 100—or produce a different scaling error for another currency.
The international currency-code standard, ISO 4217, specifies three-letter alphabetic and three-digit numeric currency codes, as well as the decimal relationship for currencies that have minor units. ISO describes relationships such as division by 100 or 1,000 on its currency-code overview. The official record for ISO 4217:2015 says the edition was published in August 2015 and confirmed in 2021; the record also shows review activity in 2026.
Rank #2
- Precise Detection: PONNOR USD/EUR money counter has 4 detection methods to detect all kind of bills UV,IR,MG and DD;If fake/broken money are detected, the screen will be red and the alarm will sound.
- 3.7” Large LCD Display: PONNOR cash counter with a built in 3.7” super large LCD screen, it can clearly display different data and greatly reduces the possibility of false counts; the external display provides dual views, allows customers from different angles to read data at any time.
- Innovative 12 keys design: 12 keys provide a full set of numeric keyboards and 11 functions, including auto, manual, batch, add, value, currency, set, UV, IR, DD, MG; the numeric keys allow you to not only calculate fixed number of notes in batch functions, but you can freely set the number of notes you want to calculate.
- Efficient and Accurate Counting: The upgraded version of the bill counter has upgraded and enhanced motor has higher speed and stable accuracy;it can count more than 1300 bills/min smoothly, and the noise keep less than 60dB; the large hopper capacity can hold 200 bills, meeting the maximum demand of various occasions.
- The plug is American standard and has a voltage of 110V, which can only be used in the United States. If you want to use it in other countries or for other voltages, please purchase a voltage converter, otherwise it may cause damage to the machine.
Shinder’s examples illustrate why the currency must travel with the amount: yen and won use no minor unit, while Bahraini and Kuwaiti dinars use three decimal places. Those examples are from his account; consult current currency metadata rather than hard-coding a short list.
How the refund path could have failed differently
The article says the refund path had the opposite scaling error: it multiplied when it should have used the correct currency scale. In the reported case, the payment provider rejected refunds larger than the original charge, preventing that path from producing the over-refund the code might otherwise have attempted. That safeguard limited this particular failure; it does not make incorrect refund calculations safe.
Rank #3
- WORKING MODE: Mixed Denomination Counting(MDC)/Single Denomination Counting(SDC)/Count The Number(CNT)/ Batch/ Accumulation. In MDC Mode, The Money Counter Machine Can Automatically Recognize The Value Of The Bill, All Denominations Can Be Read And Counted. Quantity And Amount Will Show At The Same Time. Supports USD, CAD, MXN, EUR, and GBP.
- BANK-GRADE COUNTERFEIT DETECTION: With Infrared Detection, Ultraviolet Detection, Magnetic Detection, And Dimensional Detection, Al-N60 Counterfeit Bill Detector Provides The Most Accurate Detection Results. If Counterfeit Or Residual Money Is Detected, The Screen Will Be Red And The Alarm Will Sound.
- DUAL-SCREEN DISPLAY: 3.5” TFT Screen Adopts The Latest Liquid Crystal Display Technology, With Higher Definition. Easy And Fast Reading. The External Monitor Provides Dual Views And Allows Customers From Different Angles To Read Data At Any Time.
- EFFICIENT AND ACCURATE: The Mixed Denomination Money Counter Can Count More Than 1200 Bills/Min Smoothly, Fast, And Accurately With Low Noise. The Large Hopper Capacity Can Hold 200 Bills, Meeting The Maximum Demand Of Various Occasions.Please follow the correct money placement method in the user manual or video guide. This will reduce the probability of money jamming by 60%.
- PACKAGING & GUARANTEE: 1 X AL-N60 Bill Counter, 1 X External Display, 1 X Power Cord, 1x IR Calibration Paper, 1 X Nylon Brush, 1 XClean Cloth, 1 X Fuse, 1 X User Manual, 8 X Currency Straps. We Provide Extended Product Support And Upgrade The Software Free for Lifetime. ( No Information On The Box For Your Privacy)
Controls Shinder recommends
Shinder’s lessons focus on making currency scale an explicit part of payment handling. They are recommendations drawn from the incident, not a guarantee that any one control is sufficient on its own.
- Centralize amount conversion. Use one shared money library or conversion layer that reads currency exponent data, rather than scattering fixed division or multiplication across handlers.
- Keep the amount and currency together. Pass and store a value with its currency code so downstream code cannot silently interpret a bare number using the wrong scale.
- Reject unknown currencies. Fail clearly when a currency code has no recognized metadata instead of guessing a decimal scale or falling back to two places.
- Contract-test several scales. Exercise payment and refund flows with currencies that have zero, two, and three decimal places. Verify that the amount sent, the amount recorded, and the amount used by fulfilment remain consistent.
- Reconcile orders and payments by currency. Compare order totals with payment totals using matching currency codes and make mismatches visible before fulfilment depends on them. Shinder says daily reconciliation would have revealed a 99 percent gap on the first morning; that is his counterfactual, not an observed reconciliation result.
The lesson: a payment amount is not just a number
Shinder says the currency code was present beside the amount in every call for four years, but the handler did not need to read it until the company began accepting a currency with a different minor-unit convention. That is the core design failure: the code had the information needed to interpret the value, but its conversion rule discarded that context.
Rank #4
- 【Valuation】The money counter can calculate the total value of bills. Combined with the ADD mode, it can calculate the total amount of multiple stacks of the same denomination. (The cash counter machine cannot automatically recognize bill denominations, and the value needs to be set manually.) Suitable for small businesses, retail shops, office environments, and food service operations with daily cash processing needs.
- 【Counterfeit Detection】The money counting machine uses advanced UV/MG/IR/DD/DBL/HLF/CHN counterfeit detection technologies. When the machine detects counterfeit, damaged, half, or double-fed banknotes, the display will turn red and the alarm will sound for added counting security.
- 【3.7” Bright LCD display】: The 3.7” large display can clearly read and display different data, and the attached external display can help you read data from multiple angles at any time
- 【Fast & Efficient Counting】Built with an optimized feeding system, the banknote counting machine can count up to 1,300 Notes/Min with stable and smooth performance. The hopper capacity is 200 banknotes. Supports COUNT/ADD/BATCH/AUTO/MANUAL modes to meet different counting preferences and business cash handling needs.
- 【Packaging】1 x Money Counter, 1 x Power Cord, 1 x Brush, 1 x External Display, 1 x Spare Parts Kit, 4 x Currency Straps, 1 x Instruction Manual. For added privacy, the outer packaging does not display product details related to the cash counting machine. We provide lifetime services support.
Payment systems should treat currency as part of the amount’s meaning from receipt through storage, order checks, refunds, and reconciliation. In this incident, the customer paid correctly; a fixed-scale assumption made the company’s records say otherwise.
Quick Recap
Best Value
- Huge Time Saver: Bill counter machine mixed denomination counts and reports total value, clear breakdown of quantity and value by Denom, and serial number. Besides, supports multi-currency value counting(USD/MXN/CAD/EUR/COP/LBP/ILS/etc). Available to print them all with MUNBYN printer. Ideal for the small business, gas station, church, bank
- 2 CIS Tech: ①Unlike common mixed denomination money counter, IMC01 money counting machine scans both sides of each bill with dual sensors, detects and reads 2 sides of every counted bill like human eyes. ②The accuracy of value counting is 3 times than 1 CIS machine, no matter brand new, worn, slight ripped and damaged banknote. ③Serial Number Recognition and record for Money Tracking.
- Ideal For Business: Money counter machine mixed denomination boosts your efficiency on cash counting job with the following functions: Mixed denomination, manual sorting based on first denomination or currency, ADD, BATCH, ADD & BATCH, Auto/Manual counting, PRINT(Need MUNBYN printer). Ideal for grocery stores or casinos to deal with heavy cash-counting jobs
- Business Guard: The mixed denomination currency counter has 11 counterfeit detection methods to ensure your bills’ authenticity. Cash counter mixed denomination saves your effort and keeps you peace of mind when you deal with heavy cash counting work. 2CIS, UV, MG, IR, MT, and SN Recognition, effective against Superdollar.[Privacy Protection] For your privacy and security, there is no information about the cash counting machine on the outer box, ensuring the safety of your cash business
- Powerful Services: ①Two years of quality protection, lifetime software upgrade, and 24-hour technical support available on weekdays. ②Upload Data Instructions or Troubleshooting Video for any issues, please click 【FAQ(PDF)】on our listing.③The product will be continuously updated and improved, supporting firmware upgrades
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
