Question

The human retina contains cells called rods and cones that absorb light and change it to electric signals sent to the brain. There are approximately 120,000,000 rods and 6,000,000 cones in a retina. How is the number of rods in a human retina written in scientific notation?

 

Answer 1

To write this in scientific notation, we need to move the decimal point to the left so that there is only one non-zero digit to the left of the decimal point. We can do this by dividing the number by 10 until we get a number between 1 and 10. The number of times we divide by 10 gives us the exponent.

 

Starting with 120,000,000, we can divide by 10 seven times to get:

 

12,000,000.0

 

This number is between 1 and 10, so we can write it in scientific notation as:

 

1.2 x 10^8

 

Therefore, the number of rods in a human retina is written in scientific notation as 1.2 x 10^8.

The number of rods in a human retina is 120,000,000.