example.r

pum_mod2 <- function(conv_factor, value) {
    mod <- 0
    case_when(
       value < conv_factor ~ mod <- ceiling(conv_factor - value),
       value %% conv_factor != 0 ~ mod <- ceiling((value / conv_factor) * conv_factor - value),
    )
    
    return(mod)
}

pum_mod <- function(conv_factor, value) {
    # for values smaller than the conversion factor, we just need add the difference
    if (value < conv_factor) {
        mod <- ceiling(conv_factor - value)
    # for values larger than the conversion factor, we calc the remainder to get up to a number that is evenly divisible
    } else if ((value %% conv_factor) != '0') {
        mod <- ceiling((value / conv_factor) * conv_factor - value)
    } else {
        mod <- 0
    }

    return(mod)
}