Military Flight Aptitude Test: Decimals

Some questions on the Military Flight Aptitude Test will require you to work with decimals. You can express a fraction as either a percentage or a decimal. To convert a fraction into a decimal, just divide the numerator by the denominator. For example, 1/4 is 1 / 4 or .25.

Rounding up or down

Sometimes your decimals don’t come out as cleanly as .25; you may have a decimal that has more decimal places than your calculator can register. In these instances, you round the number to cut off the run of decimal places.

To round a decimal, decide which decimal place you want to round to. (The first place to the right of the decimal point is the tenths place; the second is the hundredths; the third is the thousandths; and so on.)

Look one place to the right of your desired rounding place; if the number there is lower than five, the number in your rounding place stays the same. If the number to the right of the rounding place is five or higher, the number in your rounding place bumps up to the next higher number.

For the purposes of a military flight aptitude test, you can round extended decimals to the nearest hundredth. For example, 5/9 is 5 divided by 9 or

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(The bar over the 5 means that number repeats to infinity.) To round it to the hundredths place, you check the third number to the right of the decimal place (thousandths); that number is 5, so you round up to the next number to get 0.56.

Adding and subtracting decimals

Addition and subtraction are easy with decimals. You just have to remember to line up the columns correctly before you start. Align the terms so that the decimal points match up, and you’ll be fine.

Multiplying decimals

When multiplying decimals, you multiply as if you’re multiplying whole numbers and then adjust the placement of the decimal point based on the total number of decimal places in the factors. For example, to multiply 1.111 x 1.03, you treat the problem as 1111 x 103 = 114433.

Next, you add up the number of decimal places in the problem: 1.111 has three decimal places, and 1.03 has two, for a total of five places. Starting at the farthest right decimal place in the answer, you move five places to the left and drop in the decimal point to get 1.14433, which you can round off to 1.14.

Dividing decimals

When dividing a decimal by a whole number, you first move the decimal point in the dividend (the number you’re dividing into) to the right until you have a whole number; perform the division with the whole numbers and then move the decimal place back to the left the same number of spaces you moved it to the right.

For example, to divide 0.3 by 2, you move the decimal point in 0.3 one space to the right so that the equation is 3 / 2 = 1.5. Then you move the decimal point back the same amount, or one space, to the left to get your final answer of 0.15.

If the decimal is divided by another decimal, you move the decimal point in the divisor (the number that is going into the other number) just enough to make it a whole number. Move the decimal point in the dividend the same number of spaces (even if the dividend won’t be a whole number) and divide as you normally would.

For example, take .002 / .08. First, you move the point out by two decimal places to get 0.2 / 8, which is the same as 0.200 / 8, or 0.025. (You can add zeros to the right of a decimal point without changing the value of the number.) In this case, you don’t have to move the decimal point in the final answer.

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