Basic Math & Pre-Algebra All-in-One For Dummies (+ Chapter Quizzes Online). Mark Zegarelli

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      Whichever way you write it, the idea is the same: When you divide 12 pretzel sticks equally among three people, each person gets 4 of them.

       When you divide one number by another, the first number is called the dividend, the second is called the divisor, and the result is the quotient. For example, in the division from the earlier example, the dividend is 12, the divisor is 3, and the quotient is 4.

Applying the Big Four Operations to Larger Numbers

      So, be honest. Are you’re feeling a bit shaky about how to apply the Big Four operations to larger numbers, especially long division? If so, don’t worry. Just use this section as a handy reference for remembering how to do stacked addition, subtraction, and multiplication, as well as everybody’s favorite, long division.

      Calculating stacked addition

      Stacked addition allows you to add large numbers in a systematic way.

      For example, to add , stack the numbers up in a column format as follows:

      Next, starting in the ones’ column and working from right to left, add the numbers and place each result below the line:

      Thus, .

      In most cases when you add, the calculation will involve carrying at least one digit from one column to the next.

      For example, suppose you want to add . Begin by adding in the ones’ column, then write the 2 below the line and carry the 1 to the next column:

      Next, add in the tens’ column, then write the 4 below the line and carry the 2:

      To complete the problem, add :

      Therefore, .

      Performing stacked subtraction

      As with addition, stacked subtraction allows you to subtract larger numbers systematically.

      For example, to subtract , stack the numbers as follows:

      Now, as with addition, start in the ones’ column and work right to left, this time subtracting each pair of numbers in the column, and place each result below the line:

      So .

      In most cases when you subtract, the calculation will involve borrowing at least one digit from one column to the next.

      For example, suppose you want to subtract :

      To begin, you want to subtract in the ones’ column. However, 3 is less than 4, so to subtract, you need to borrow 1 from the tens’ column, changing the 5 to 4. Then, this 1 that you borrowed is worth 10 in the ones’ column, so add it to the 3, changing it to 13:

      Now, you can subtract , and place this result in the ones’ column below the line:

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