standard index form

This form is used to deal with very large numbers and very small numbers.

Numbers are written as a number between 1 and 10 multiplied by power 10.

For example, if we are dealing with large numbers the decimal point must be moved until the number is between 1 and 10. Then, we have to count how many places the point has moved, and that is the power 10:

• 193 in standard index form is 1.93 × 10²
• 500 000 in standard index form is 5 × 100 000 = 5 × 10⁵

We also move the decimal point until the number is between 1 and 10 if we are dealing with small numbers. Then, we have to count how many places the point has moved, and put a minus sign in front of it. That is the power 10:

• 0.000 004 in standard index form is 4 × 10⁻⁶
• 0.000 635 in standard index form is 6 × 10⁻⁴