# Null and nan on my counting app

**URL:** https://community.thunkable.com/t/null-and-nan-on-my-counting-app/1849798
**Category:** Questions about Thunkable X
**Created:** [April 26, 2022, 4:02pm UTC](https://community.thunkable.com/t/null-and-nan-on-my-counting-app/1849798 "2022-04-26T16:02:31Z")
**Posts on this page:** 1
**Showing post:** 6

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### Author: ![muneer](https://sea1.discourse-cdn.com/flex015/user_avatar/community.thunkable.com/muneer/32/75210_2.png) [@muneer](https://community.thunkable.com/u/muneer)
#### Post date: [April 26, 2022, 8:23pm UTC](https://community.thunkable.com/t/null-and-nan-on-my-counting-app/1849798/6 "2022-04-26T20:23:39Z")

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The blocks in the screen Opens are not correct.

You need to check the variable first before assigning it to any other component.

See this simple example  
 ![image](https://us1.discourse-cdn.com/flex015/uploads/thunkable/original/3X/1/6/16ffad3ad03af62cb2846731a7b80bc9cdce71ba.png)

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