How do you write 780,000 in scientific notation?

The scientific notation equivalent of 780,000 is 7.8 x 105.

Why is 780,000 written as 7.8 x 105 in scientific notation?

780,000 = 7.8 × 100,000

and 100,000 = 105 (see powers of 10)

so 780,000 = 7 × 105

Both 780,000 and 7 × 105 have the same value, just shown in different ways.

Scientific notation is a standard way of writing very large and very small numbers so that they’re easier to both compare and use in computations. To write in scientific notation, follow the form

N x 10a

where N is a number between 1 and 10, but not 10 itself, and a is an integer (positive or negative number).

You move the decimal point of a number until the new form is a number from 1 up to 10 (N), and then record the exponent (a) as the number of places the decimal point was moved. Whether the power of 10 is positive or negative depends on whether you move the decimal to the right or to the left. Moving the decimal to the right makes the exponent negative; moving it to the left gives you a positive exponent.

See a step by step guide on how to write numbers in scientific notation at Dummies.com.