# How to increment a number counter field?

**URL:** <https://community.glideapps.com/t/how-to-increment-a-number-counter-field/1054>\
**Category:** Ask for Help\
**Created:** [October 10, 2019, 12:07am UTC](https://community.glideapps.com/t/how-to-increment-a-number-counter-field/1054 "2019-10-10T00:07:58Z")\
**Posts on this page:** 1\
**Showing post:** 15

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**Author:** ![Robert\_Petitto](https://sea2.discourse-cdn.com/flex002/user_avatar/community.glideapps.com/robert_petitto/32/25193_2.png) [@Robert\_Petitto](https://community.glideapps.com/u/Robert_Petitto)\
**Post date:** [April 29, 2020, 3:35am UTC](https://community.glideapps.com/t/how-to-increment-a-number-counter-field/1054/15 "2020-04-29T03:35:17Z")

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> [@Reducing a sheet cell’s value when a form is submitted](https://community.glideapps.com/t/reducing-a-sheet-cell-s-value-when-a-form-is-submitted/8057/2):
>
> Yep! I have a version of this in my Inventory app ([itemstore.glideapp.io](http://itemstore.glideapp.io)). Set a quantity for an item, then every time a user buys an item, the quantity decreases: Basically, set an initial quantity in the shop tab. Do a multiple relation to the SKU between shop tab and purchases tab. Rollup the count of purchases within the relation. Subtract the count from the quantity using a math column. Display the result. Hide the buy button once the inventory reaches zero.

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