# Multiplication function or similar
**URL:** https://discourse.nodered.org/t/multiplication-function-or-similar/22452
**Category:** General
**Created:** [1 March 2020 15:13 UTC](https://discourse.nodered.org/t/multiplication-function-or-similar/22452 "2020-03-01T15:13:59Z")
**Posts on this page:** 13
**Page:** 1
### Author:  [@gianluca.ginoble](https://discourse.nodered.org/u/gianluca.ginoble)
#### Post date: [1 March 2020 15:13 UTC](https://discourse.nodered.org/t/multiplication-function-or-similar/22452/1 "2020-03-01T15:13:59Z")
Hi all.
I want to multipicate two different RANDOM nodes to use the multiplication result in another node.
How can i implement this function?
---
### Author:  [@Colin](https://discourse.nodered.org/u/Colin)
#### Post date: [1 March 2020 15:41 UTC](https://discourse.nodered.org/t/multiplication-function-or-similar/22452/2 "2020-03-01T15:41:25Z")
What do you mean by RANDOM nodes? Do you mean a particular node type that you have installed?
If you mean that you have two messages coming in from different nodes and you want to join the messages so that you can use data from both nodes in a function node (for example) then have a look at the example in the cookbook on joining streams.
[https://cookbook.nodered.org/basic/join-streams](https://cookbook.nodered.org/basic/join-streams)
---
### Author:  [@gianluca.ginoble](https://discourse.nodered.org/u/gianluca.ginoble)
#### Post date: [1 March 2020 19:26 UTC](https://discourse.nodered.org/t/multiplication-function-or-similar/22452/3 "2020-03-01T19:26:58Z")
Hi and thanks for your reply.
I've just read your link but i think it doesn't help me.
You can see attached my flow.
Instead of the JOIN node i would to use a multiplication node or similar.
How can implement it?
```auto
[{"id":"24529235.0f95ae","type":"tab","label":"Multiplication","disabled":false,"info":""},{"id":"fb705d35.038ff","type":"ui_chart","z":"24529235.0f95ae","name":"","group":"31de20bd.63b6c","order":1,"width":0,"height":0,"label":"Tensione [V]","chartType":"line","legend":"true","xformat":"HH:mm:ss","interpolate":"linear","nodata":"","dot":false,"ymin":"0","ymax":"250","removeOlder":"180","removeOlderPoints":"","removeOlderUnit":"1","cutout":0,"useOneColor":false,"colors":["#00ff00","#aec7e8","#ff581c","#2ca02c","#98df8a","#7ff21b","#ff9896","#7cf5a2","#c5b0d5"],"useOldStyle":false,"outputs":1,"x":805,"y":126,"wires":[[]]},{"id":"b4df74d8.46c978","type":"random","z":"24529235.0f95ae","name":"Tensione","low":"215","high":"225","inte":"true","property":"payload","x":396,"y":168,"wires":[["fb705d35.038ff","c3ddab68.cd52d8","65a88d12.bb7e44","6357798a.e0c228"]]},{"id":"105332c0.e8260d","type":"inject","z":"24529235.0f95ae","name":"","topic":"Tensione","payload":"1","payloadType":"num","repeat":"1","crontab":"","once":false,"onceDelay":0.1,"x":154,"y":168,"wires":[["b4df74d8.46c978"]]},{"id":"b6a79024.a0608","type":"random","z":"24529235.0f95ae","name":"Corrente","low":"5","high":"20","inte":"true","property":"payload","x":375,"y":231,"wires":[["58d168ef.117d58","2f65c37a.86dc9c","65a88d12.bb7e44"]]},{"id":"9943c87f.d52f98","type":"inject","z":"24529235.0f95ae","name":"","topic":"Corrente","payload":"1","payloadType":"num","repeat":"1","crontab":"","once":false,"onceDelay":0.1,"x":154,"y":231,"wires":[["b6a79024.a0608"]]},{"id":"58d168ef.117d58","type":"ui_chart","z":"24529235.0f95ae","name":"","group":"31de20bd.63b6c","order":2,"width":0,"height":0,"label":"Corrente [A]","chartType":"line","legend":"true","xformat":"HH:mm:ss","interpolate":"linear","nodata":"","dot":false,"ymin":"0","ymax":"60","removeOlder":"180","removeOlderPoints":"","removeOlderUnit":"1","cutout":0,"useOneColor":false,"colors":["#1f77b4","#aec7e8","#ff7f0e","#2ca02c","#18df0a","#d62728","#ff9896","#9467bd","#c5b0d5"],"useOldStyle":false,"outputs":1,"x":805,"y":252,"wires":[[]]},{"id":"cb4e6015.edf25","type":"ui_chart","z":"24529235.0f95ae","name":"","group":"31de20bd.63b6c","order":3,"width":0,"height":0,"label":"Potenza istantanea [kW]","chartType":"line","legend":"true","xformat":"HH:mm:ss","interpolate":"linear","nodata":"","dot":false,"ymin":"0","ymax":"60","removeOlder":"180","removeOlderPoints":"","removeOlderUnit":"1","cutout":0,"useOneColor":false,"colors":["#1f77b4","#aec7e8","#e45aea","#2ca02c","#98df8a","#d62728","#ff9896","#9467bd","#c5b0d5"],"useOldStyle":false,"outputs":1,"x":950,"y":420,"wires":[[]]},{"id":"58f0cb97.862454","type":"debug","z":"24529235.0f95ae","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","x":910,"y":336,"wires":[]},{"id":"2f65c37a.86dc9c","type":"ui_gauge","z":"24529235.0f95ae","name":"","group":"834e9290.5975f","order":2,"width":0,"height":0,"gtype":"gage","title":"Corrente","label":"units","format":"{{value}}","min":0,"max":"30","colors":["#00b500","#e6e600","#ca3838"],"seg1":"10","seg2":"20","x":795,"y":210,"wires":[]},{"id":"c3ddab68.cd52d8","type":"ui_gauge","z":"24529235.0f95ae","name":"","group":"834e9290.5975f","order":1,"width":0,"height":0,"gtype":"gage","title":"Tensione","label":"units","format":"{{value}}","min":0,"max":"230","colors":["#00b500","#e6e600","#ca3838"],"seg1":"110","seg2":"220","x":795,"y":84,"wires":[]},{"id":"65a88d12.bb7e44","type":"join","z":"24529235.0f95ae","name":"","mode":"custom","build":"object","property":"payload","propertyType":"msg","key":"topic","joiner":"\\n","joinerType":"bin","accumulate":false,"timeout":"","count":"","reduceRight":false,"reduceExp":"","reduceInit":"","reduceInitType":"","reduceFixup":"","x":680,"y":336,"wires":[["58f0cb97.862454","cb4e6015.edf25"]]},{"id":"6357798a.e0c228","type":"debug","z":"24529235.0f95ae","name":"","active":false,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","x":616,"y":42,"wires":[]},{"id":"31de20bd.63b6c","type":"ui_group","z":"","name":"Gruppo3","tab":"4e9aa3f5.60126c","order":1,"disp":false,"width":10,"collapse":false},{"id":"834e9290.5975f","type":"ui_group","z":"","name":"Gruppo5","tab":"4e9aa3f5.60126c","order":2,"disp":false,"width":10,"collapse":false},{"id":"4e9aa3f5.60126c","type":"ui_tab","z":"","name":"3-Trend variabili","icon":"fa-line-chart","order":3,"disabled":false,"hidden":false}]
```
---
### Author:  [@Colin](https://discourse.nodered.org/u/Colin)
#### Post date: [1 March 2020 20:14 UTC](https://discourse.nodered.org/t/multiplication-function-or-similar/22452/4 "2020-03-01T20:14:12Z")
You need to do the Join first, then multiply the numbers, which should be available in msg.payload.
I don't know what type the Random node is, you haven't told us, but for the Join to work the two inputs must have different topics. Also you haven't told the Join node to give you a joined message after two message parts are received.
---
### Author:  [@Colin](https://discourse.nodered.org/u/Colin)
#### Post date: [1 March 2020 21:39 UTC](https://discourse.nodered.org/t/multiplication-function-or-similar/22452/5 "2020-03-01T21:39:00Z")
Apart from considering the solution I would be fascinated to know why you want to multiply two random numbers together.
---
### Author:  [@gianluca.ginoble](https://discourse.nodered.org/u/gianluca.ginoble)
#### Post date: [2 March 2020 10:33 UTC](https://discourse.nodered.org/t/multiplication-function-or-similar/22452/6 "2020-03-02T10:33:46Z")
Random node creates a random number.
I use this node to make a demo.
---
### Author:  [@zenofmud](https://discourse.nodered.org/u/zenofmud)
#### Post date: [2 March 2020 11:48 UTC](https://discourse.nodered.org/t/multiplication-function-or-similar/22452/7 "2020-03-02T11:48:44Z")
Might I make a suggestion, have one inject node going to two change nodes that set the msg.topic.
Also add a new join node in and replace the existing one. For some reason, the internals of the node thinks it should be doing the join using 'bin' when it should be 'str'. I've seen this happen before but thought it was something I did but I think it is a bug in the join node which I'm going to investigate.
In your case, just add a new `join` node, set the settings up like this:
and after the join you could use a function node or a change node to multiply the two values. Here is an example (with the dashboard info removed.) Showing what I mean:
```auto
[{"id":"ab242326.56c6c8","type":"random","z":"a340b780.deade8","name":"Tensione","low":"215","high":"225","inte":"true","property":"payload","x":400,"y":80,"wires":[["d3965c13.571df8"]]},{"id":"a6ecace0.d9f3d","type":"inject","z":"a340b780.deade8","name":"","topic":"Start","payload":"1","payloadType":"num","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":90,"y":140,"wires":[["a4fd6efe.59b158","f777c593.0262e8"]]},{"id":"d5058fd1.e36c18","type":"random","z":"a340b780.deade8","name":"Corrente","low":"5","high":"20","inte":"true","property":"payload","x":400,"y":200,"wires":[["d3965c13.571df8"]]},{"id":"13abfe36.bce56a","type":"debug","z":"a340b780.deade8","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","targetType":"full","x":710,"y":180,"wires":[]},{"id":"851c2a9f.e4256","type":"debug","z":"a340b780.deade8","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","targetType":"full","x":550,"y":180,"wires":[]},{"id":"d3965c13.571df8","type":"join","z":"a340b780.deade8","name":"","mode":"custom","build":"object","property":"payload","propertyType":"msg","key":"topic","joiner":"\\n","joinerType":"str","accumulate":false,"timeout":"","count":"2","reduceRight":false,"reduceExp":"","reduceInit":"","reduceInitType":"","reduceFixup":"","x":530,"y":140,"wires":[["befd85e3.12838","851c2a9f.e4256"]]},{"id":"befd85e3.12838","type":"change","z":"a340b780.deade8","name":"","rules":[{"t":"set","p":"payload","pt":"msg","to":"payload.Tensione*payload.Corrente","tot":"jsonata"}],"action":"","property":"","from":"","to":"","reg":false,"x":740,"y":140,"wires":[["13abfe36.bce56a"]]},{"id":"f777c593.0262e8","type":"change","z":"a340b780.deade8","name":"","rules":[{"t":"set","p":"topic","pt":"msg","to":"Corrente","tot":"str"}],"action":"","property":"","from":"","to":"","reg":false,"x":240,"y":200,"wires":[["d5058fd1.e36c18"]]},{"id":"a4fd6efe.59b158","type":"change","z":"a340b780.deade8","name":"","rules":[{"t":"set","p":"topic","pt":"msg","to":"Tensione","tot":"str"}],"action":"","property":"","from":"","to":"","reg":false,"x":240,"y":80,"wires":[["ab242326.56c6c8"]]}]
```
---
### Author:  [@zenofmud](https://discourse.nodered.org/u/zenofmud)
#### Post date: [2 March 2020 12:00 UTC](https://discourse.nodered.org/t/multiplication-function-or-similar/22452/8 "2020-03-02T12:00:06Z")
Also can you let me know
- what version of NR and node.js (see node-red startup log)
- what platform/os you are using
Thanks
---
### Author:  [@gianluca.ginoble](https://discourse.nodered.org/u/gianluca.ginoble)
#### Post date: [2 March 2020 12:44 UTC](https://discourse.nodered.org/t/multiplication-function-or-similar/22452/9 "2020-03-02T12:44:25Z")
Hi and many thanks for your reply.
I've just resolved using a function node after join node.
However i save your solution for further implementation.
This is the cose used in function node:
var prodotto = {payload: msg.payload.Corrente \* msg.payload.Tensione};
return prodotto;
---
### Author:  [@zenofmud](https://discourse.nodered.org/u/zenofmud)
#### Post date: [2 March 2020 12:47 UTC](https://discourse.nodered.org/t/multiplication-function-or-similar/22452/10 "2020-03-02T12:47:16Z")
And I figured out whet the bug is in the join node and am reporting it.
---
### Author:  [@gianluca.ginoble](https://discourse.nodered.org/u/gianluca.ginoble)
#### Post date: [2 March 2020 12:48 UTC](https://discourse.nodered.org/t/multiplication-function-or-similar/22452/11 "2020-03-02T12:48:20Z")
These are my system info:
Node-RED version: v1.0.3
Node.js version: v10.19.0
Linux 4.19.57+ arm LE
Raspberry model B+
Dashboard version 2.19.4 started at /ui
---
### Author:  [@zenofmud](https://discourse.nodered.org/u/zenofmud)
#### Post date: [2 March 2020 13:13 UTC](https://discourse.nodered.org/t/multiplication-function-or-similar/22452/12 "2020-03-02T13:13:52Z")
FYI issue raised to fix the bug see: [https://github.com/node-red/node-red/issues/2491](https://github.com/node-red/node-red/issues/2491)
If you do hit this issue, you can fix the node by switching the 'to create' option to 'a String' and changing the 'join using' to 'a/z' thn changing the 'to create' back to what you originally had.
---
### Author:  [@system](https://discourse.nodered.org/u/system)
#### Post date: [16 March 2020 13:13 UTC](https://discourse.nodered.org/t/multiplication-function-or-similar/22452/13 "2020-03-16T13:13:53Z")
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