Procedure used:

Adding and Subtracting Decimals:

Step 1 : write the numbers in a column with the decimal points and corresponding plzce values lined up. (Insert additional zeros as placeholders after the last digit to the right of the decimal point.)

Step 2: Add or substract the digits in columns from right to left, as you would whole numbers. The decimal point in the answer should be lined up with the decimal points from the original numbers"

Calculation:

Given: \(\displaystyle{54.2}+{23.993}+{3.87}.\)

By using the above mentioned procedure, add the three decimals in the expression \(\displaystyle{54.2}+{23.993}+{3.87}\) as follows.

Line up the decimal points and insert additional zeros as placeholder.

\(\displaystyle{54.200}\)

\(\displaystyle{23.993}\)

\(\displaystyle\underline{{+{3.870}}}\)

Add the digits with common place values and then line up the decimal point in the required answer.

\(\displaystyle{54.200}+{23.993}+\underline{{+{3.870}}}={82.063}\)

Hence, the simplified form the expression \(\displaystyle{54.2}+{23.993}+{3.87}\ {i}{s}\ \underline{{{82.063}}}\)