1)  Write the numbers in column form.

2)  Decimal points should come in one column.

3)  There should be the same number of digits after the decimal point in each number. [If required put zeroes at the extreme right of the decimal point as it does not change the value of the number.]

1. Align the decimal points of the numbers.
2. If necessary, add zeros to the right of the decimal point to make sure both numbers have the same number of decimal places.
3. Add the digits in each column, starting from the rightmost column.
4. If the sum of the digits in a column is 10 or greater, carry the "tens" place value to the left and add it to the next column.
5. Continue adding the digits in each column, carrying over as necessary, until you reach the leftmost column.
6. Write the decimal point in the sum directly below the decimal points of the numbers being added.

The examples are given below for your better understanding -

3    .     5 0 0

1 6    .     0 8 0

+ 1 2 5   .     0 7 3

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1 4 4   .     6 5 3

b) Add 10.1, 100.01, 1.1011, 1000

1 0    .    1 0 0 0

1 0 0    .    0 1 0 0

1   .    1 0 1 1

+ 1 0 0 0   .    0 0 0 0

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1 1 1 1   .    2 1 1 1