Subtraction

Subtraction occurs when one quantity is taken away from another quantity, resulting in a smaller quantity. To subtract two numbers, the minuend (the number being subtracted from) is written above the line and the subtrahend (the number being subtracted) is written below the line. The line represents the separation between the numbers. The numbers are then aligned so that their digits line up directly below each other. The minuend digit in each column is then subtracted from the subtrahend digit in that column, and the difference is written in its place. If the minuend digit is smaller than the subtrahend digit in a column, the minuend digit is borrowing from the column to its left. The number 1 is written above the column being borrowed from, and the minuend digit in that column is decreased by 1. The borrowing process is then continued in the next column to the left.

Learning subtractions facts can be difficult for some students. A good way to help teach them is to use manipulatives, such as counters or a number line. Start with small numbers and work up to larger ones. It is also important to stress that when subtracting, the order in which the numbers are subtracted does not matter. Help students to understand this by using a number line and having them cross off the numbers as they are subtracted.