## Elementary Algebra

1.5 $\times$ $10^{7}$
We need to write 15,000,000 as the product of a number greater than or equal to 1 and less than 10, and an integral power of 10. The number greater than or equal to 1 and less than 10 will be 1.5. The decimal point has moved 7 places to the right, so the exponent of 10 will be 7. So, 15,000,000 = 1.5 $\times$ $10^{7}$