Formula for custom number format in Google Sheets (e.g. 5M –> 5,000,000; 50k –> 50,000; etc)

I’ve been trying to figure this out for a bit but everything I’ve tried doesn’t work. A quick search brought me to the conversion from full number format to condensed format (5,000,000 –> 5M; 50,000 –> 50k), however I need to do the reverse conversion (5.4M –> 5,400,000; 50k –> 50,000). I’m being given in the number in the condensed format with “B”, “M”, and “k” but I need to type out the full number which is becoming a right pain.

Anyone have a formula for this conversion?