# Question Video: Using the Part-Whole Method to Identify a Decimal Number Mathematics • 4th Grade

The big square below represents one whole. What decimal is represented by the shaded area?

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### Video Transcript

The big square below represents one whole. What decimal is represented by the shaded area?

First, let’s figure out how many tiny squares there are in the big square. There are 10 rows and 10 columns. 10 times 10 equals 100. Our big square is then 100 square units. 100 units are inside. There are nine shaded units. That means that our shaded area is nine out of 100, nine 100ths.

We need to take this fraction and convert it into a decimal. When we’re working with decimals, we use the place value system, to the left of the zero units, to the right of the zero 10ths, and then 100ths. We have nine 100ths.

We can put our nine in the 100ths position. We have zero tenths and zero whole numbers, zero units. So the decimal that’s represented by the shaded area is nine 100ths, 0.09.