# Verify values in a table are correct

**URL:** <https://cl.desmos.com/t/verify-values-in-a-table-are-correct/2851>\
**Category:** Questions\
**Tags:** validation, correctness\
**Created:** [March 6, 2021, 6:19pm UTC](https://cl.desmos.com/t/verify-values-in-a-table-are-correct/2851 "2021-03-06T18:19:04Z")\
**Posts on this page:** 1\
**Showing post:** 5

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**Author:** ![Daniel\_Grubbs](https://yyz1.discourse-cdn.com/flex031/user_avatar/cl.desmos.com/daniel_grubbs/32/719_2.png) [@Daniel\_Grubbs](https://cl.desmos.com/u/Daniel_Grubbs)\
**Post date:** [March 8, 2021, 1:28am UTC](https://cl.desmos.com/t/verify-values-in-a-table-are-correct/2851/5 "2021-03-08T01:28:38Z")

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You probably want `countNumberUsage`. Check out this post (you can still use numericValue instead of evaluateAt):

> [@Checking Math Input for Correct Rational Expression](https://cl.desmos.com/t/checking-math-input-for-correct-rational-expression/2829/3):
>
> The more complicated (but stable) method is to evaluate a function AND check that certain numbers were used (since you’re looking for a particular format), so for your example above: #student expression exp=this.latex #student input as a function f=simpleFunction(exp) check= f.evaluateAt(3)=0 and f.evaluateAt(2)=-0.2 and countNumberUsage(exp,3)=1 and countNumberUsage(exp,2)=1 and countNumberUsage(exp,1)=1 You want to evaluate at as many values you feel is adequate. I only did a few but…

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