Counting up after filling in number

Hello,

Ik have a question.
I use the promp command to enter a number and store it as a variable.
I use this in combination with the while script to loop til the end of the csv.
My wish is that after i fill in a number one time, it does a +1 every time and use this to type the number +1 in a specified filed.

Thnx
Below the script

{
“Name”: “testblock”,
“CreationDate”: “2019-4-23”,
“Commands”: [
{
“Command”: “prompt”,
“Target”: “Type hier de extensie”,
“Value”: “extension”
},
{
“Command”: “comment”,
“Target”: “Onnet data”,
“Value”: “”
},
{
“Command”: “csvRead”,
“Target”: “onnet.csv”,
“Value”: “”
},
{
“Command”: “echo”,
“Target”: “Status = {!csvReadStatus}, line = {!csvReadLineNumber}”,
“Value”: “”
},
{
“Command”: “while”,
“Target”: “”{!csvReadStatus}\" == \"OK\"", "Value": "" }, { "Command": "echo", "Target": "status = {!csvReadStatus}, line = {!csvReadLineNumber}", "Value": "" }, { "Command": "comment", "Target": "Na dit blok beginnen met bouwen", "Value": "" }, { "Command": "comment", "Target": "", "Value": "Add virtual onnet users." }, { "Command": "click", "Target": "xpath=//*[@id=\"buttonbarbottom\"]/td/input[3]", "Value": "" }, { "Command": "storeEval", "Target": "{extension}+1",
“Value”: “number”
},
{
“Command”: “type”,
“Target”: “name=lastName”,
“Value”: “{!col2}" }, { "Command": "type", "Target": "name=clidLastName", "Value": "{!col2}”
},
{
“Command”: “type”,
“Target”: “name=firstName”,
“Value”: “{!col1}" }, { "Command": "type", "Target": "name=clidFirstName", "Value": "{!col1}”
},
{
“Command”: “type”,
“Target”: “name=phoneNumber”,
“Value”: “{!col3}" }, { "Command": "type", "Target": "name=extension", "Value": "{number}”
},
{
“Command”: “select”,
“Target”: “id=virtualOnNetCallTypeName”,
“Value”: “label=Default”
},
{
“Command”: “clickAndWait”,
“Target”: “xpath=//*[@id=“buttonbarbottom”]/td/input[2]”,
“Value”: “”
},
{
“Command”: “storeEval”,
“Target”: "{!csvReadLineNumber}+1", "Value": "!csvReadLineNumber" }, { "Command": "store", "Target": "true", "Value": "!errorIgnore" }, { "Command": "echo", "Target": "Reading CSV line No. {!csvReadLineNumber} ",
“Value”: “!errorIgnore”
},
{
“Command”: “csvRead”,
“Target”: “onnet.csv”,
“Value”: “”
},
{
“Command”: “store”,
“Target”: “false”,
“Value”: “!errorIgnore”
},
{
“Command”: “endWhile”,
“Target”: “”,
“Value”: “”
}
]
}

Same question as here: Use promt, variable and more