# Red blood cells in human body (scientific notation word problem) | Pre-Algebra | Khan Academy | Summary and Q&A

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August 20, 2013
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Red blood cells in human body (scientific notation word problem) | Pre-Algebra | Khan Academy

## TL;DR

The video explains how to calculate the number of red blood cells in a human body using scientific notation.

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### Q: What is the total volume of blood in the human body?

The total volume of blood in the human body is 5 liters.

### Q: What fraction of the total volume of blood is made up of red blood cells?

40% of the total volume of blood is made up of red blood cells.

### Q: What is the volume of each red blood cell?

Each red blood cell has a volume of approximately 90 times 10 to the negative 15 liters.

### Q: How can we calculate the number of red blood cells in the body?

To calculate the number of red blood cells, divide the total volume of red blood cells (40% of 5 liters) by the volume of each red blood cell (90 times 10 to the negative 15 liters).

## Summary & Key Takeaways

• The human body has 5 liters of blood, with 40% of it being red blood cells.

• Each red blood cell has a volume of approximately 90 times 10 to the negative 15 liters.

• To calculate the number of red blood cells, divide the total volume of red blood cells by the volume of each red blood cell.