# How do you write 540 in scientific notation?

$540 = 5.4 \cdot {10}^{2}$
For instance, US debt is now about $18 trillion. This huge number looks like $18000000000000$(dollars) Too many zeroes, is not it. Say, you want to compare it with the distance from Earth to Sun, which is $150$million kilometers, that in standard units accepted by physicists - meters - looks like $150000000000$(meters) Also a lot of zeroes. To easier see the magnitude of a number it is represented in scientific notation as a number from 1 to 10 multiplied by a number 10 in some power. Thus, $18000000000000 = 1.8 \cdot {10}^{13}$$150000000000 = 1.5 \cdot {10}^{11}$Now it's obvious that the first number more than in $100$times greater than the second because the front parts, called mantissa, ($1.8$in one case, $1.5$in another) are close to each other, while the powers of $10$, called exponent, are significantly different, one is $13$, while another is $11$, so the multiplier of $10$to some power is greater in the first case by ${10}^{2}$, that is the first number is greater than the second by at least a factor of $100\$.