# Countdown in steps using math.js

**URL:** <https://community.homey.app/t/countdown-in-steps-using-math-js/30621>\
**Category:** Questions & Help\
**Created:** [May 30, 2020, 12:23pm UTC](https://community.homey.app/t/countdown-in-steps-using-math-js/30621 "2020-05-30T12:23:31Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![Heronimus](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/heronimus/32/3564_2.png) [@Heronimus](https://community.homey.app/u/Heronimus)\
**Post date:** [May 30, 2020, 12:23pm UTC](https://community.homey.app/t/countdown-in-steps-using-math-js/30621/1 "2020-05-30T12:23:31Z")

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I have a challenge with Better Logic - math.js , maybe someone can help me with it.

The idea is as follows:  
A countdown of 120 seconds  
Goal:

1. Say per 10 seconds the countdown value
2. Say for every second in the last 10 seconds the countdown value

I have the following flow  
TRIGGER: When timer value has changed  
AND : BETTER Logic Math.js expression is true  
mod(countdownvar,10)==0  
OR : countdownvar value less then 10  
THEN : say countdownvar

The expression doesn’t work. What is the right formula to use?![TestCountdown|325x500]

 ![TestCountdown](https://us1.discourse-cdn.com/flex025/uploads/athom/original/3X/d/b/db2a751ab2c1a07dd82701d3ebd736bc169155b5.png)

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**Author:** ![robertklep](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/robertklep/32/160628_2.png) [@robertklep](https://community.homey.app/u/robertklep)\
**Post date:** [May 30, 2020, 12:52pm UTC](https://community.homey.app/t/countdown-in-steps-using-math-js/30621/2 "2020-05-30T12:52:40Z")

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Perhaps start with using `mod` instead of `Mod`. If that doesn’t work, start with a simpler version, for instance without the tag but just a hardcoded value.

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<div class="post-metadata">

**Author:** ![Heronimus](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/heronimus/32/3564_2.png) [@Heronimus](https://community.homey.app/u/Heronimus)\
**Post date:** [May 30, 2020, 2:13pm UTC](https://community.homey.app/t/countdown-in-steps-using-math-js/30621/3 "2020-05-30T14:13:18Z")

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Thank you Robert. I brought back the expression to  
{{(divide(10,10)-mod(10,10))==0}}

But still a false as answer.

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<div class="post-metadata">

**Author:** ![robertklep](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/robertklep/32/160628_2.png) [@robertklep](https://community.homey.app/u/robertklep)\
**Post date:** [May 30, 2020, 2:21pm UTC](https://community.homey.app/t/countdown-in-steps-using-math-js/30621/4 "2020-05-30T14:21:43Z")

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`1 - 0 == 0`

That is false.

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<div class="post-metadata">

**Author:** ![Heronimus](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/heronimus/32/3564_2.png) [@Heronimus](https://community.homey.app/u/Heronimus)\
**Post date:** [May 30, 2020, 2:22pm UTC](https://community.homey.app/t/countdown-in-steps-using-math-js/30621/5 "2020-05-30T14:22:00Z")

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![afbeelding](https://us1.discourse-cdn.com/flex025/uploads/athom/original/3X/0/0/005dc0d379458b359b5c894f690b30b5ae13b39d.png)

Thanks for your suggestion. That helped debugging the formula

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<div class="post-metadata">

**Author:** ![Heronimus](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/heronimus/32/3564_2.png) [@Heronimus](https://community.homey.app/u/Heronimus)\
**Post date:** [May 30, 2020, 2:39pm UTC](https://community.homey.app/t/countdown-in-steps-using-math-js/30621/6 "2020-05-30T14:39:46Z")

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or much more simple  
mod(soundbrdtest1,10)==0