"You Must Use Whole Numbers" error?

Hello Qualtrics Community, We've had several of our survey takers have this error - when they are entering into a total sum question, they get the error saying that they have to use whole numbers... Even though they are using whole numbers. Some were using Chrome, some Firefox, and restarting the survey doesn't seem to fix their problem. Does anyone know why this is happening or how to fix it? Thanks, Rebecca