# Prévois message

**URL:** <https://discourse.nodered.org/t/prevois-message/35405>\
**Category:** General\
**Created:** [5 November 2020 21:30 UTC](https://discourse.nodered.org/t/prevois-message/35405 "2020-11-05T21:30:37Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![micke0079](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/micke0079/32/31494_2.png) [@micke0079](https://discourse.nodered.org/u/micke0079)\
**Post date:** [5 November 2020 21:30 UTC](https://discourse.nodered.org/t/prevois-message/35405/1 "2020-11-05T21:30:38Z")

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Hey guys !  
I'm searching for a solution to subtract the previous message with the new one. Any ideas ?  
Thanks

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**Author:** ![zenofmud](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/zenofmud/32/316_2.png) [@zenofmud](https://discourse.nodered.org/u/zenofmud)\
**Post date:** [5 November 2020 23:07 UTC](https://discourse.nodered.org/t/prevois-message/35405/2 "2020-11-05T23:07:00Z")

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- store the first message in a context variable
- use a join node to join the two messages

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**Author:** ![dceejay](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/dceejay/32/38_2.png) [@dceejay](https://discourse.nodered.org/u/dceejay)\
**Post date:** [5 November 2020 23:09 UTC](https://discourse.nodered.org/t/prevois-message/35405/3 "2020-11-05T23:09:26Z")

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See this thread from only yesterday - [Multiply two variables](https://discourse.nodered.org/t/multiply-two-variables/35380)

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**Author:** ![system](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/d073cd938eafa2e558d7c2cd59003b3ef4963033.png) [@system](https://discourse.nodered.org/u/system)\
**Post date:** [4 January 2021 23:09 UTC](https://discourse.nodered.org/t/prevois-message/35405/4 "2021-01-04T23:09:52Z")

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