Input_number subtraction

Configuration
1

Hello,

I have a Shelly 1 PM connected to a water heater, witch turn on if water temp is below 42ºC and turn off if wter temp is higer than 50ºC
I creat an automation that notifies me when Shelly turns on and save the total consumption to a input.number.
When it turns off I get a notification also and save the total consumption to another input.number.
What I want and I can’t figure it out is on the notification when it turns off get information about the subtration of the final input.number and the inicial input.number.

input_number:
  consumption_start:
    name: Consumo inicio
    min: 0
    max: 999999999

  consumption_end:
    name: Consumo fim 
    min: 0
    max: 999999999

  energy_used:
    name: Energia Consumida 
    min: 0
    max: 999999999

automation:

  - alias: Cilindro On
    initial_state: true
    trigger:
      - platform: state
        entity_id: switch.shelly_shsw_pm_d8bfc019c514
        from: 'off'
        to: 'on'
    action:
        - service: input_number.set_value
          data_template:
            entity_id: input_number.consumption_start
            value: "{{ states.sensor.shelly_shsw_pm_d8bfc019c514_total_consumption.state }}"
        - service: telegram_bot.send_message
          data_template:
            target: !secret telegram_chatid1
            message: >
              Cilindro ligou, temperatura da água são {{states.sensor.shelly_shsw_pm_d8bfc019c514_2_temperature.state}}ºC, e consumo total atual são {{states.sensor.shelly_shsw_pm_d8bfc019c514_total_consumption.state}} KWh
            disable_notification: true


  - alias: Cilindro Off
    initial_state: true
    trigger:
      - platform: state
        entity_id: switch.shelly_shsw_pm_d8bfc019c514
        from: 'on'
        to: 'off'
    action:
        - service: input_number.set_value
          data_template:
            entity_id: input_number.consumption_end
            value: "{{ states.sensor.shelly_shsw_pm_d8bfc019c514_total_consumption.state }}"
        - service: input_number.set_value
          data_template:
            entity_id: input_number.energy_used
            value: "{{ states('input_number.consumption_end') - states('input_number.consumption_start') }}"
        - service: telegram_bot.send_message
          data_template:
            target: !secret telegram_chatid1
            message: >
              Cilindro desligou, temperatura da água são {{states.sensor.shelly_shsw_pm_d8bfc019c514_2_temperature.state}}ºC, e consumiu {{states.input_number.energy_used.state}} KWh
            disable_notification: true
2

All states are strings and you can’t subtract them. You have to convert them to numbers.

            value: "{{ states('input_number.consumption_end') | float - states('input_number.consumption_start') | float }}"