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Decimal Arithmetic


We assume that you are familiar with the decimal number system and arithmetical operations on integers (whole numbers).

Two decimal numbers may be added as follows:

  • the numbers are written one below the other with the decimal points vertically aligned
  • the numbers are added as if they are whole numbers
  • a decimal point is placed in the sum such that it is directly below the decimal points in the numbers being added

Note that we can assume all numbers to be added have the same number of digits after decimal point, as adding zeros at the end of a decimal number does not change the value of the number.

For example,
3 = 3.0 = 3.00, and 2.3 = 2.30 = 2.300.


Example 1A.

Let us calculate:   123.45 + 37.50

answer = 160.95


Example 1B.

Each time you click "New Example" a new example will be shown. Click "=" to see the answer.












Exercise 1.

Perform the following additions without using a calculator:












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