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LESSON: Rounding Decimals

READ: Rounding Very Large Numbers

Rounding Very Large Numbers to Decimal Representations of Thousands, Millions, etc.

We just finished rounding some very tiny numbers, but what about really large numbers? Can we use rounding to help us to examine some really large numbers?

Here are the sales totals for the three top movies according to movie sales.

  1. Star Wars IV - $460,998,007
  2. Avatar - $558,179,737
  3. Titanic - $600,788,188

Those are some big numbers! Here is where rounding can be very helpful. We can round each of these numbers to the nearest hundred million.

First, let’s find the hundred millions place.

  1. Star Wars IV - $460,998,007
  2. Avatar - $558,179,737
  3. Titanic - $600,788,188

The place that is highlighted is the hundred millions place. Now we want to round to the nearest hundred million. We do this by looking at the number to the right of the place that we are rounding.

Let’s look at each movie individually.

1. Star Wars IV - The number after the 4 is a 6, so we round up to a 5. The rest of the numbers are zeros.

500,000,000

2. Avatar - The number after the 5 is a 5, so we round up to 6. The rest of the numbers are zeros.

600,000,000

3. Titanic - The number after the 6 is a zero. So the 6 stays the same and the rest of the numbers are zeros.

600,000,000

If we want to compare these numbers now we can see that Avatar and Titanic had the highest sales and Star Wars IV had the least highest sales. Sometimes we can get confused reading numbers with so many digits in them. Rounding the numbers helps us to keep it all straight.