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Math K-Plus

Definition Of Decimal Numbers

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What Are Decimal Numbers


Decimal Numbers are an extension of Whole Numbers, and continue to infinity: .

Let's define a decimal number by example. You buy a pizza and have it cut into ten slices. Here is the pizza in fraction form: 1/10 + 1/10 + 1/10 + 1/10 + 1/10 + 1/10 + 1/10 + 1/10 + 1/10 + 1/10 = 1 pizza.

Here is the pizza in decimal form (1/10 = 0.1): 0.1 + 0.1 + 0.1 + 0.1 + 0.1 + 0.1 + 0.1 + 0.1 + 0.1 + 0.1 = 1 pizza. We know that a pizza cut into ten slices in fraction form is 1/10 per slice. So how is 1/10 = 0.1? We convert the fractional number in to a decimal number using division.

  • Step 1: 1/10 Here is one slice of a whole pizza. We can not divide 1 by 10.
  • Step 2: 10/10 So we multiply 1 by 10 to get 10 or said another way we move the decimal point one place to the right of 1 to get the number 10. We can divide 10 by 10 evenly. The answer is one.
  • Step 3: 1 In step 2, we moved the decimal point one place to the right. Now to finish solving the problem we must to move the decimal point one place to the left. The number changes from 1 to .1 or 0.1. This is the decimal form of one tenth.
  • Step 4: 1/10 = 0.1

One last example. Two people eat the pizza cut into ten pieces. So each per gets five slices: 10/2 = 5. How do we represent this as a decimal number? Let's do the math: 0.1 + 0.1 + 0.1 + 0.1 + 0.1 = 0.5. Each person gets one half of the pizza.