The sum we got can encourage us to go even further! After all, we can get 100, 10, 1, 0.1, and 0.01 by raising the number 10 to integer powers: to the power 2, 1, 0, -1, and -2, respectively. In other words, we can also write: Suppose that you've taken up astronomy recently and would like to know the gravitational force acting between the Earth and the Moon. For the calculations, we need the masses of the two objects (denote the Earth's by M₁ and the Moon's by M₂) and the distance between them (denoted by R). We have: Don't ask us how they found the mass of the Earth, as there isn't any scale big enough to weigh the entire planet. As for the circumference, talk to Eratosthenes. in the left form field (or top field for the mobile version of the calculator) you should see a value of 0.39370079 inches;

Converting from decimals to fractions is straightforward. It does, however, require the understanding that each decimal place to the right of the decimal point represents a power of 10; the first decimal place being 10 1, the second 10 2, the third 10 3, and so on. Simply determine what power of 10 the decimal extends to, use that power of 10 as the denominator, enter each number to the right of the decimal point as the numerator, and simplify. For example, looking at the number 0.1234, the number 4 is in the fourth decimal place, which constitutes 10 4, or 10,000. This would make the fraction 1234 Fraction subtraction is essentially the same as fraction addition. A common denominator is required for the operation to occur. Refer to the addition section as well as the equations below for clarification. aThis time, we indeed see the digits as the first factors in each multiplication. Moreover, the second factors have a lot in common - they consist of a single 1 with some zeros (possibly none). in the right form field (or bottom field for the mobile version) you should see a value of 2.54 cm; The first multiple they all share is 12, so this is the least common multiple. To complete an addition (or subtraction) problem, multiply the numerators and denominators of each fraction in the problem by whatever value will make the denominators 12, then add the numerators. EX: When a is a fraction, this essentially involves exchanging the position of the numerator and the denominator. The reciprocal of the fraction 3 Now, this is more like it! We don't know about you, but for us, short is beautiful, in mathematics at least.

Non-Americans often refer to the standard form in math in connection with a very different topic. To be precise, they understand it as the basic way of writing numbers (with decimals) using the decimal base (as opposed to, say, the binary base), which we can decompose into terms representing the consecutive digits. The expanded form is a way to write a number as a sum, each summand corresponding to one of the number's digits. In our case, the sum would be: Now, this looks even worse than the previous example; it doesn't have commas in between! Thankfully, there are tools - like our standard form calculator - to make our lives easier. So, what is the standard form of the above numbers? and the circumference is... actually, the 40,075 km doesn't look that bad, does it? Well, we could use a length converter and change it to 4.0075 × 10⁴ km, but is it better that way? If we needed to change it to millimeters, then maybe it'd be a better idea, but the kilometer form seems perfectly usable.

It might seem artificial to write a sum of the products, like 1×100 or 4×1, but that's just what the expanded form is. Anyway, if scientists had to write all of those zeros every time they calculated something about our planet, they'd waste ages! It's much easier to recall how to write a number in standard form and say that the mass of Earth is, in fact, When multiplying decimals, placement of the decimal point is very important. Since there is one decimal digit in each factor, there must be two decimal digits in the product. This is because tenths x tenths = hundredths. Estimating the product lets us verify that the placement of the decimal point is correct, and that we have a reasonable answer. For example, if your product was 68.992 miles, then you would know that you made a multiplication error after comparing it with your estimate. Let's look at some more examples of multiplying decimals.