Subtraction is when you take one number away from another number. Rules for subtraction become more intricate, based on the type of numbers you are subtracting.
Basic Subtraction Rules
If you subtract zero from any number, the result is the original number. For example, 11 – 0 = 11. Any number you subtract from itself produces zero. For example, 7 – 7 = 0. When you subtract multidigit numbers, write the larger number above the smaller and then align the columns by place value. Subtract one column at a time, from right to left. In the problem, 389 – 24, right-align the 24 so the four is under the nine and the two is under the eight. Then, subtract 24 from 389 to give you 365.
Sometimes, when you subtract multidigit numbers, you see a larger digit under a smaller digit. In this instance, you must borrow. For example, look at this subtraction problem: 95 – 48. This looks like you need to take away five from eight, but, of course, you cannot. Essentially, you turn the five into a 15. To do this, borrow 10 from the column to the left and change the nine into an eight. This makes the five essentially a 15. Subtract 15 – 8 to get 7, then subtract 8 – 4 to get 4. Your answer is 47.
When you subtract decimal numbers, align the decimal points so that the digits’ place value is consistent. You may need to add zeroes to a number so that both figures have the same number of digits. For example, if you subtract 5.2 – 3.01, place the three directly under the five. Then, align the decimal points so that the decimal point for 3.01 is directly under the decimal point for 5.2. Then, place the zero from 3.01 underneath the two in 5.2. Then, place a zero at the end of 5.2 so that you have 5.20; place the one from 3.01 underneath this new zero. Subtract 3.01 from 5.20 to result in 2.19.