How is using mental math to add with decimals like using mental math to add whole numbers? how is it different?

Using mental math to add with decimals is like using mental math to add whole numbers because the actual thing is we are adding the place values in both the cases and they different as in case of whole numbers we start from the ones place but in case of decimal numbers we first separate it into whole numbers and decimals to add by using mental math separately, after solving the sum we write both parts together and that is the answer.

For example to add 6.40+7.30

Take after decimal portion separately 0.40+0.30=0.70

and 6+7=5+1+5+2=10+3=13

write together it becomes 13.70.

so 6.40+7.30=13.70.