You might have noticed how certain items automatically stack together. Well there is a way to get some from that stack without having to send or sell the whole stack. Here you go

1. Click on account

2. Click on Inventory

3. Find the item you want to take from but don't click on it

4. Hold down the shift button

5. While holding down the shift button click the item, then click on an empty slot

6. A box will pop up asking "How many Stacks do you want to split?" this is where you put the number you want to take away from the stack. So if you only want 1 item from the stack then you put 1 into the box. If you want 5 or 10 then you put those numbers in the box.

Is there a way to do it on mobile phone?

Nope, no way to split stacks on mobile atm, unfortunately. :(

I try to split them when I'm on a computer, and just keep a few separate small or individual stacks in my inventory.