Convert string to integer without rounding - IBAN Check

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Posted on by Jurbe48

Hi,

I want to validate IBAN numbers. The steps I take in Power Automate are the following:

I get an IBAN number, for example: BE68 5390 0754 7034
I chop everything up: substring(...)
I replace the letters with their number values 111468 5390 0754 7034
I do the reordering : concat(part1, part2, par3): 5390 0754 7034 11 14 68

Now the final step is the modulo 97 on the result, the problem however is the following:

Because of the concat() I used earlier my 'number' actually is a strig value
mod() expects an integer
if I do the following: int(539007547034111468), Power Automate returns me: 539007547034111500, which is a rounded version of the initial value. This limitation is described here: Power Automate: int Function - Manuel T. Gomes. This rounded version does not allow met to do the modulo 97 as the input is different.

So what I need is either a way to convert large number strings to integers in Power Automate, a way to concatenate integers without returning me a string value or just a completely other way to validate IBAN numbers.

Any advice?

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Jurbe48 18 on at

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***UPDATE***

I took a different approach:

Took the strig: 539007547034111468

Split it in two parts: 53900754703411 and 1468

Converted both of them to integers: int(53900754703411) and int(1468)

Added them together by multiplying the first part with 10000 and then using the add() function: add(539007547034110000, 1468)

But again this didn't work as the add() function also has a character limitation (https://manueltgomes.com/reference/powerautomate-function-reference/add-function/) I again got this result: 539007547034111500

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w.p 8,339 Super User 2025 Season 2 on at

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@Jurbe3147

That's a limitation—try using AI assistance with AI Prompt.

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w.p 8,339 Super User 2025 Season 2 on at

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Without any calculation, the number is automatically converted, even in Excel.

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Jurbe48 18 on at

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@w.p, thanks for your suggestion. Unfortunately I don't have access to AI builder credits.

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w.p 8,339 Super User 2025 Season 2 on at

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Sorry, I take it back—it's not reliable.

Unless someone else has a solution, my workaround is using Office Script in Excel, but the file must be stored in OneDrive or SharePoint.

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w.p 8,339 Super User 2025 Season 2 on at

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running into another issue, Office Scripts doesn't currently support Big Integer.

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w.p 8,339 Super User 2025 Season 2 on at

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@Jurbe3147

GOOD NEWS

Office Script

function main( workbook: ExcelScript.Workbook, numberStr: string, divisor: number ) { let remainder = 0; for (let i = 0; i < numberStr.length; i++) { const digit = parseInt(numberStr[i]); remainder = (remainder * 10 + digit) % divisor; } return remainder; }

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