Multiplying Decimals Type your name and send: Next slide

To Multiply: Place the number with more digits on top. Multiply Count the number of decimal places (from the right) in the question. Make sure that you have the same number of decimal places in your answer. Next slide

Example: 5.63 x x two one three. Next slide

2.3 x 1.4 When multiplying these two numbers together, it is easier to put them into a grid. Next slide

2.3 x For now let’s cheat and pretend that it is not Decimals – just remember there are two numbers to the right in the question. The first thing to do is partition the numbers into tens and units. 2 decimals to the right Next slide

2.3 x Multiply the number above the box with that on the left, writing the answer inside the box, as shown below What goes here? 2 decimals to the right Next slide

2.3 x The next step is to add up the rows, putting the answer in the boxes on the right What goes here? 2 decimals to the right Next slide

2.3 x Now add up the totals on the right to NEARLY give the answer What goes here? 2 decimals to the right Next slide

2.3 x How many numbers to the right in the question? decimals to the right Next slide

2.3 x How many numbers to the right in the answer? decimals to the right Next slide

Now you can work out multiplication using the grid method, you will find long multiplication easy! This is a little different from the grid method, as the numbers are set out in columns… Next slide

5.1 x 4.2 becomes x Qwizdom question – what would your estimate be? Whole numbers only using nearest nice number? Next slide

5.1 x x Remember what we did using the grid method? The first thing to do, is multiply the tens of the top number with the tens and units of the bottom number. Next slide

5.1 x x Next, multiply the units of the top number by the tens and units of the bottom number. 50 x x 2 Next slide

5.1 x x Don’t forget to write down the multiplication next to the answer. 50 x x 2 1 x x 22 Next slide

5.1 x x The NEARLY final step is to add up the column of numbers and put the total at the bottom. 50 x x 2 1 x x Qwizdom – what would the final total be? Next slide

5.1 x x What is the actual answer? 50 x x 2 1 x x Next slide

Multiplication Properties Commutative Property of Multiplication: Factors can be multiplied in any order. Example: 12 x 5 = 5 x 12 Associative Property of Multiplication: Factors can be grouped in any way. Example: (2 x 3) x 5 = 2 x (3 x 5) Identity Property of Multiplication: The product of any number and one is that number. Example: 18 x 1 = 18 Next slide

LO: To be able to multiply with decimals I understand this idea fully. I have some understanding but I need more practice. I don’t understand this idea at all and need to work again on this unit of work. A B C End of slide show