Where does a decimal point go?

ALWAYS Between the units number and the tenths decimal number.

e.g. 4.5

'4' is the units ' 5' is the tenths decimal number.

or

102. 345

'2' is the units number and ;3; is the tenths decimal number.

When adding or subtracting decimals keep the decimal point directly below each other. It makes for far easier manipulation

Hence (adding)

102.345

004.500 (Note the use of trivial zeroes '0'.

____-----

106.845

======

Rather than

102.345

4.5

Much more difficult and far easier to make a mistake.