1. DP , you mean decimal points?
87.6564 is already written in decimals points.
it is a combination of a whole number and a decimal points.
=> 87 is the whole number where 8 is tens and 7 is the ones.
=> 6564 is the decimal numbers where 6 next to the decimal point is tenths, 5 is hundredths, 6 is the thousandths and 4 is the ten thousandths.
When you round this number to its nearest tenths, it becomes 87.7