Inventory product computation and conversion - php

Question

I am coding inventory of products. Now I am in the process of computing or converting the items into a larger unit.
For example:
Product A: 1 box = 12 bottles
The user can input a data like 3 boxes and 13 bottles when adding a transaction. And the new value for Product A will be 3 boxes and 13 bottles in storage. Data will save into database tbl_transaction.
How can I automatically turn/convert the items as a whole like 4 boxes and 1 bottle in storage to add in my tbl_storage?
I have tried this formula but I am afraid it is not accurate when the number of bottles is in the decimal point.
$bottles = 13;
$box = 12;
$remaining_in_bottle = number_format($bottles / $box);// this will only convert the bottle into box (also tried float but not sure what I am doing)
$total_box = 3 + ???;
echo $total_box." boxes and ".$remaining_in_bottle ." bottles in storage

Answer 1

I am assuming the user is inputing just digits as values for boxes and bottles, but if not you will simply need to extract these values from the string before performing the following calculations:
Code: (Demo)
$bottles_per_box=12;
$user_input_bottles=13;
$user_input_boxes=3;
if($user_input_bottles>$bottles_per_box){
// add truncated integer to box count. DO NOT USE ROUND(), USE FLOOR()
$user_input_boxes+=floor($user_input_bottles/$bottles_per_box);
// store remainder after division
$user_input_bottles=$user_input_bottles%$bottles_per_box;
// ^-- modulo operator
}
echo "New Bottles Total: $user_input_bottles\n";
echo "New Boxes Total: $user_input_boxes\n";
Output:
New Bottles Total: 1
New Boxes Total: 4

Answer 2

I assume that you want to input different for tbl_transaction and tbl_storage.
CODE
//Max bottle per box
$box_max_bottles = 12;
//User Input
$input_box = 3;
$input_bottle = 13;
//Transaction
$transaction = (($input_box > 1) ? $input_box . ' boxes' : $input_box . ' box')
. ' and ' . (($input_bottle > 1) ? $input_bottle. ' bottles' : $input_bottle. ' bottle'). ' in storage';
//Data will save into database tbl_transaction
echo $transaction;
//Get the remainder which is the remaining bottle
$total_bottle = $input_bottle % 12;
//Get the total boxes and divide the bottle into 12
$total_box = floor($input_box + ($input_bottle / 12));
echo "<br />";
//Storage
$storage = (($total_box > 1) ? $total_box . ' boxes' : $total_box . ' box')
. ' and ' . (($total_bottle > 1) ? $total_bottle . ' bottles' : $total_bottle . ' bottle'). ' in storage';
//Data will save into database tbl_storage
echo $storage;
OUTPUT
Transaction
3 boxes and 13 bottles in storage
Storage
4 boxes and 1 bottle in storage