6 − 1 = 5, so put a 5 in the answer of the hundreds column to give our final answer. Step 3: Finally take 1 away from 6 in the hundreds column. Take 8 from 15 and write the answer (7) at the bottom of the tens column. So instead of 5 tens, we now have 15 tens.ġ5 is larger than eight, so we can perform our subtraction in the tens column. We are not adding ‘1’ to the tens, we are lending ‘1 lot of 10’. Move the 1 to the tens column and write it in front of the 5. Cross through the 7 and write 6 in the hundreds column to avoid mistakes later. This can be a tricky concept and we look at it in greater detail below: We have 7 in the hundreds column, so we ‘borrow’ 1 for the tens column, leaving us with 6 in the hundreds. We need to borrow a number from the hundreds column. Next we need to subtract the numbers in the tens column. In our example, we need to subtract eight from five (5 − 8), but 8 is larger than 5, so we cannot do this as we would end up with a negative number. Step 2: Using the same approach as an addition calculation, we work across the columns from right to left. Step 1: First we perform a subtraction on the numbers in the Units column on the right, then write the answer at the bottom in the same column. We write the starting number first and the number we are taking away underneath, taking care to make sure the numbers are in the correct columns. In this example we are going to take £180 away from £755. How much money does Mike have left after he has paid his rent? Suppose that Mike earns £755 a week and pays £180 a week for rent. Phoebe has 4 more sweets than Luke, the difference in sweets is 4.įor more complex subtraction, where using counting is not appropriate, it is useful to write our numbers in columns one above the other-similar to an addition calculation. Starting with the smaller number (5) and count up to the larger number (9). If Phoebe has 9 sweets and Luke has 5 sweets what is the difference? Simple subtraction can be carried out in the same way as addition, by counting or using a number line: In this case we have written the numbers in the same order as before, but we have taken their positive or negative value into account.įor a more detailed explanation and examples, see the section on Subtraction in Special Situations: Zero and Negative Numbers below. Here is the last example re-written to give the correct answer:Ĩ − 5 − 3 = 0 as before, and − 5 + 8 − 3 = 0, giving the same answer. However, the ‘+’ symbol is very important if we change the order, as are the ‘−‘ symbols that precede 5 and 3. In our example, 8 is a positive number, so we could write it as ‘+ 8’ and it would be correct, but convention says that we do not need to write the ‘+’ symbol. The reason that the answers are different is not because we have put the numbers in the ‘wrong’ order, but because we have not taken care to notice whether they are positive or negative. Similarly 8 − 5 − 3 = 0, but 5 − 8 − 3 = −6, which is a completely different answer. We can see that we have the same numerical answer (3), but that its value is different: 3 in the first calculation, but minus 3 (−3) in the second. Usually with a subtraction, we write the number we are subtracting from first, and the numbers we are taking away in any order after that. However, when we are performing a subtraction, we need to take extra care with the order of the numbers. When we are performing an addition calculation, the order in which we add the numbers does not matter.Ĩ + 3 + 5 is the same as 3 + 8 + 5 and gives us the same answer, 16. This simply means 2 less than zero or 2 below zero.įor more information, see our page on Positive and Negative Numbers. Numbers that have a negative value are written with a preceding ‘−‘, so minus two is written as −2. Understanding Statistical DistributionsĬaution is needed when using the '−' sign.Area, Surface Area and Volume Reference Sheet.Simple Transformations of 2-Dimensional Shapes.Polar, Cylindrical and Spherical Coordinates.Introduction to Cartesian Coordinate Systems.Introduction to Geometry: Points, Lines and Planes. ![]()
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