in this video we're going to focus on multiplying numbers with decimals so let's start with a basic example first what is 4. 6 multiplied 7 well first we need to multiply 6 * 7 6 * 7 is 42 so we need to put the first number two and carry over the four next let's multiply 4 * 7 4 * 7 is 28 and we need to add the four on top 28 + 4 that's 32 now notice that we have one number to the right of a decimal point so therefore in our answer we should have one number to the right of a decimal point so the answer is 32. 2 now let's try another example let's multiply 3.
9 by 5. 6 feel free to try this one if you want to so first let's multiply 9 * 6 9 * 6 is 54 so we're going to write the four and then we're going to carry over the five next let's multiply 3 * 6 3 * 6 is 18 and 18 + 5 is 23 now let's move on to the five let's multiply five and 9 5 * 9 is 45 so we need to write the five but we need to add a zero first and then we'll write the five carry over the four next let's multiply 5 * 3 5 * 3 is 15 + 4 that's 19 now what we need to do is add 4 + 0 is 4 3 + 5 is 8 2 + 9 is 11 carry over the 1 1 + 1 is two now notice that we have two numbers to the right of a decimal point so therefore in our answer we should have two numbers to the right of a decimal point so the final answer is 2184 and that's it now let's multiply 12 9 by 3. 7 feel free to try this problem so first let's multiply 9 * 7 9 * 7 is 63 so we're going to write the three and carry over the six next let's multiply 2 * 7 2 * 7 is 14 + 6 that's going to be 20 so we're going to write the zero and carry over the two next we have 1 * 7 which is 7 + 2 that's equal to 9 now let's add a zero let's get rid of these numbers so now we're going to multiply 3 * 9 3 * 9 is 27 let's carry over the two and then we'll multiply 2 * 3 which is 6 6 + 2 that's 8 and then finally 1 * 3 which is just three now let's add the numbers 3 + 0 is 3 0 + 7 is the same thing 9 + 8 is 17 carry over the one 3 + 1 is 4 now how many numbers do we have to the right of a decimal point so here's one and here's another one so we got two numbers to the right of the decimal point our final answer should be the same so these two numbers are going to be to the right of this decimal point therefore the answer is 47.
73 let's continue working on some more examples let's multiply 14. 56% 8 * 6 8 * 6 is 48 let's carry over the four next we have 8 * 5 which is 40 + 4 so that's uh 44 we're going to carry over the next four and then 8 * 4 is 32 + 4 that's 36 so let's write 6 and then carry over the three 8 * 1 is 8 + 3 that's 11 so now let's uh let's get rid of these numbers let's add a zero and then let's multiply 2 * 6 2 * 6 is 12 carry over the 1 and then 2 * 5 is 10 + 1 that's 11 so let's carry over the next one 4 * 2 is 8 + 1 that's 9 and then 1 * 2 is just two so now we can add so this is going to be 8 4 + 2 is 6 6 + 1 is 7 1 + 9 is 10 carry over the 1 1 + 1 is 2 + 2 is 4 now where should we put the decimal so looking at the original problem the first number has two digits to the right of a decimal point and the second number only has one therefore our final answer should have a total of three numbers to the right of the decimal point so therefore the answer is 40. 768 now let's move on to some harder examples let's multiply 13 .
79 by 5. 46 so go ahead and try this problem let's begin by multiplying 9 and six 9 * 6 is 54 and let's add the five on top next we have 7 * 6 which is 42 + 5 so that's uh 47 let's carry over the four and next we have uh 6 * 3 which is 18 + 4 so that's 22 and now let's add the other two there 6 * 1 is 6 + 2 that's 8 now don't forget to add a zero so we're done with six let's move on to four four * * 9 that's 36 so let's add a three and then 4 * 7 is 28 + 3 that's 31 so let's carry over the other three and then 3 * 4 is 12 + 3 that's 15 so let's write five and carry over the 1 1 * 4 is four + one that's five so now we're going to move on to five let's get rid of the numbers on top and let's add a zero actually this time I'm going to add two zeros so now 5 * 9 that's 45 and then 5 * 7 is 35 + 4 that's 39 9 carry over the three 5 * 3 is 15 + 3 that's 18 and then 5 * 1 is 5 + 1 that's six so now let's add the numbers so this is four four 7 + 6 is 13 and then 1 2 and 1 that's 4 + 5 is 9 8 + 5 is 13 + + 9 that's 22 8 and 2 is 10 + 5 that's 15 and 6 and 1 is 7 now where should we put the decimal so looking at the original numbers the first number has two numbers to the right of the decimal point and the second number also have two numbers so therefore our final answer should have a total of four digits to the right of the decimal point which means our answer is 75 2934 now if you have your calculator you can confirm all of these answers so if you type it in 13.
