You can **multiply or divide both** value and percentage. 510 minutes is 510·60=30600 seconds:

|Value|Percentage||

|:-|:-|:-|

|30600 seconds|100%|divide both by 30600|

|1 second|0.003%|multiply both by 61|

|61 seconds|0.199%|so that's 99.801% remaining|

|1 second|0.003%|multiply both by 25|

|25 seconds|0.082%|so that's 99.918% remaining|

|1 second|0.003%|multiply both by 36|

|36 seconds|0.118%||