Math operations in Trello Automation

[Jesse Lopes]

Is it possible to use math operations in Trello rules?

For example I want to select the Nth item in a list randomly so I perform some math on the current time of day to generate a not so random number. There is a topic referencing the Nth checklist but not Nth checklist item so it is unclear if the same logic would apply.

[Hannah Humbert - Simpla Workflows · Accepted solution]

Hi @Jesse Lopes ! Welcome to the community :) it is possible to create calculations with butler and custom fields (see here under "Custom field arithmetic"). Are you able to explain a bit more how you see the calculation working? 

[Jesse Lopes]

Suppose I have a list of items numbered from 1 to N. It is possible to select the specific checklist item by "#) {*}". I don't expect for a function like rand() to be present and it hasn't shown to work in fields I have tested so far. So to generate a random integer I could instead use the current {yeardaynumber} and some math with either the modulus, ceiling, floor or truncate math functions. Further to this it is not clear in what format or fields an arithmetic expression is handled as math rather than plain text beside the custom field example.

[Hannah Humbert - Simpla Workflows]

I believe you can use number and date custom fields in your custom field equations. So yeah, if you're looking at using a random number in your calculation, you could use a variable such as the one you mentioned, or take the checklist item name value and add it to the custom field. I'm not sure how the latter would work in terms of selecting a random checklist item or what the trigger would be in this case. 

[Jesse Lopes]

Is it not possible to do arithmetic expressions outside of a custom field operation? I have tried a few arrangements of the curly braces around or next to math operations and have not yet yielded a value. Are you implying the values would have to be stored or set into a custom field in order to perform any math operations?

[Hannah Humbert - Simpla Workflows]

AFAIK, butler can only do calculations with custom fields, so yes, you would need the values to be held within custom fields in order to create a calculation.

[Jesse Lopes]

Thank you for your insight. It seems the automation route I was seeking is too complex for the Butler and will need to be done manually.