What is the numb bur 731,934,000 in standard form

That number is already in standard form.

If you need to write it in scientific notation, then do this.

731,934,000

Look at all the digits that are not zero, and place the decimal point in a way that you have a number from 1 to less than 10.

Take 731934, and place the decimal point after the 7 giving 7.31934.

The original decimal point was after the third zero, so now using the original number, count the number of decimal places you moved the decimal point. The decimal point moved 8 places to the left. That means you need an exponent of 8.