A decimal is a fraction in a sense. 2.3 is the same as 2 3/10. And 0.3 is the same as 3/10. 3/10 can be divided into thirds: 1/10+1/10+10 or 1/10+2/10 (1/10+1/5). So, you can take any decimal and count the decimal places. Remove the decimal point so that you are left with the number that formed the decimal then divide this by 1 followed by the same number of zeroes as there were decimal places. Example: 0.1234 is the same as 1234/10000. This cancels down to: 617/5000.
Going back to 0.3, we can divide the decimal further: 0.3=3/10=1/25+3/50+2/15+1/15, and so on.
When it comes to angles we can convert decimal angles into degrees, minutes and seconds. So 4.75º is 4º plus 0.75 of a degree. But a degree is 60 minutes and 0.75 is the same as 75/100=3/4. Therefore 0.75º is 3/4 of 60 minutes=3*60/4=45 minutes. And 4.75º=4º45'.
Another example:
4.7625 = 4+7625/10000 = 4+61/80 = 4º45.75' = 4º45'45", because 61/80*60=183/4=45.75, and 0.75' =45" (seconds).