Read parts of timer duration

I am creating a TTS message to have alexa repeat back an entity id. How to setup the code to have it read the minutes part only? The duration is 00:40:00. Alexa play back the code below as

zero forty

{{ state_attr('timer.ac_timer', 'duration') }}

How to adjust it to say

forty

{{ (state_attr('timer.ac_timer', 'duration'))[3:5] }}

With the code above, it is saying

zero

Then it means the timer duration is 0:40:00 and not 00:40:00.

{{ (state_attr('timer.ac_timer', 'duration'))[2:4] }}

@123
You are 100% correct. My mistake. I’ve input 00:40:00 in yaml file, and HA states it as 0:40:00
This works now. Thanks.

{{ (state_attr('timer.ac_timer', 'duration'))[2:4] }}

@123
I applied this to another automation I have where I want Alexa to read 30.1 (omitting the last digit) and NOT 30.11. Testing the code seems to work; however, the formatting seems to be off. The screenshot below shows half of the code is blue and abruptly turns to normal text.
formatting

Ignore it. It is an error with the syntax highlighter. It thinks anything with a colon in it is a key: value pair. This is only cosmetic and will not affect your message.