Multiplication - Version 1
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00:00This slide presents the overview of the chapter.
00:22Learning Objectives By the end of this chapter, you will be able
00:27to explain the count of rows, discuss equals of multiplication, explain multiplication
00:38with 0 and 1, construct the multiplication table of 10, demonstrate the multiplication
00:47of the bigger numbers with different methods.
00:54Introduction Basic mathematics involves the basic operations
00:59like addition, subtraction, multiplication and division.
01:06Here we are going to learn about multiplication in detail.
01:12Let us start with an activity.
01:15Find the odd man out from the following options.
01:32Here we can find the numbers in the form of groups of things.
01:37We can observe different objects on the screen in the form of groups.
01:42In the first one, we have 3 groups where each group consists of 2 apples in each basket.
01:50In total, we have 6 apples and the representation in the form of multiplication is as shown
01:57on the screen.
01:59In the second one, we have 2 bikes where each bike consists of 2 tyres.
02:08In total, we have 4 tyres and the representation in the form of multiplication is as shown
02:15on the screen.
02:18In the third one, we have 3 groups of bar chocolate where each group consists of 4 squares.
02:26In total, we have 12 squares and the representation in the form of multiplication is as shown
02:33on the screen.
02:35We use into as the symbol of multiplication.
02:42Now we can perform an activity to count in groups.
02:47Count in groups and find the total and write it in the boxes provided below.
03:17Here, we take an another activity to count in groups and also the total.
03:36Express the following equations in the form of multiplication.
03:47Here, we take an another activity to count in groups and also the total.
04:15Here, we take an another activity to count in groups and also the total.
04:43Let us carry out an activity to match the cap with the respective pen.
04:56Find the cap of the respective pen from the options below.
05:23Now we see the multiplication in the form of counting.
05:29Multiplication can also be in step counting.
05:32Suppose a grasshopper jumps 2 steps in a single jump and it has jumped 6 times in that way.
05:41This can be written as shown on the screen.
05:46Let us see some example problems.
05:51Express the following using multiplication.
05:55Grasshopper jump equal to 4 times 4 steps, 4 times 4 steps or 4 into 4 which is 16.
06:11Grasshopper jump equal to 3 times 5 steps, 3 times 5 steps or 3 into 5 which is 15.
06:20Grasshopper jump equal to 5 times 4 steps, 5 times 4 steps or 5 into 4 which is 20.
06:37Let us look at an example.
06:39One day a boy went to the fruit shop and thought of buying fruits for his mom.
06:45The rate chart appears as shown in the table below.
06:50If the boy wants to buy 5 kg of apples, how much will they cost?
06:56How much will 4 kilograms of oranges cost?
07:01How much will 3 kg of grapes cost?
07:06Solution For question a, given that 1 kg apples costs
07:12equal to 6 rupees, therefore 5 kg apples cost as 5 into 6 is equal to 30 rupees.
07:21For question b, given that 1 kg of oranges cost is equal to 5 rupees, therefore 4 kg
07:30oranges cost as 4 into 5 is equal to 20 rupees.
07:34For question c, given that 1 kg of grapes costs rupees 7, therefore 3 kg grapes cost
07:44as 3 into 7 is equal to 21 rupees.
07:51Here we are going to count the eggs in a tray.
07:55Here we can see a tray of eggs.
07:59There are 4 rows of eggs and in each row there are 5 eggs.
08:06Instead of counting the eggs one by one, we can do it as multiplication of the eggs with
08:12respect to the number of rows and vice versa.
08:16This could be written as shown on the screen.
08:21Let us have a look at the table of 10.
08:25Here if we observe carefully, each bundle consists of 10 pencils.
08:31By multiplying with the number of bundles with respect to the pencils in each bundle,
08:37we have the table of 10.
08:42Here we see the multiplication with 0 and 1.
08:47Add the zeros as shown on the screen.
08:51We will always get 0 irrespective of the number we are multiplying.
08:56Now add the ones as shown on the screen.
09:00Hence on multiplying with 1, we will always get the same number as the result.
09:09Now we will know equals of multiplication.
09:14Select an option from the left column and then find its match from the right column.
09:44Let us do it one more time.
10:13Let us look how the bigger numbers are being multiplied.
10:17There are three methods of multiplication.
10:21Method 1.
10:22Counting the numbers in the form of addition.
10:26Let us multiply 31 into 3.
10:29Here we can add the numbers by the successive addition of 31 up to 3 times.
10:35That is 31 plus 31 plus 31 is equal to 93.
10:43Therefore 31 into 3 is equal to 93.
10:49Method 2.
10:51Multiplying the numbers by splitting the place value.
10:55Let us multiply 31 into 3.
10:58Here we can split the numbers by their place values.
11:02For the number 31, we can split as 30 plus 1.
11:0730 into 3 is equal to 90 and 1 into 3 is equal to 3.
11:14That implies 90 plus 3 is equal to 93.
11:19Method 3.
11:21Direct multiplication using tables.
11:24Let us multiply 31 into 3.
11:27Here we can simply multiply the numbers using tables.
11:32Therefore 31 into 3 is equal to 93.
11:37Let us take another number to multiply.
11:41Let us multiply 25 into 3.
11:45Consider that 3 boys consist of 25 erasers each.
11:51Here we have grouped the erasers as tens and ones.
11:58Let us count all the groups of tens and all the groups of single erasers separately.
12:04If we observe here, we will have another ten as we count the erasers which are in singles.
12:11We can make them as one ten and the five erasers remain the same.
12:17We have 10 plus 10 plus 10 plus 10 plus 10 plus 10 plus 10 plus 5 is equal to 75.
12:28The same result can be obtained by another two types of multiplication procedures.
12:35Procedure 1.
12:37Here we can split the numbers by their place values.
12:41For the number 25, we can split as 20 plus 5.
12:4520 into 3 is equal to 60 and 5 into 3 is equal to 15.
12:52That implies 60 plus 15 is equal to 75.
12:58Therefore we can get the same result as 75 by splitting the tens and ones place values.
13:05Procedure 2.
13:07Direct multiplication using tables.
13:10We get the number 15 when 3 and 5 are multiplied.
13:14After the number which is in tens place, that is 1 is to be carried over to the tens
13:20place and above the number 2 as shown.
13:24Then multiplying the numbers 2 and 3 gives 6 tens and we will add the carried over 1
13:32here as a 10 and that becomes 7 tens.
13:38Let us do an activity to multiply the numbers.
13:42Multiply the following numbers and write it in the boxes provided below.
14:12Let us look at an example.
14:42Calculate the given problems.
14:56Here we are given 15 into 3.
15:00Where in 15, 5 is in ones place and 1 is in tens place.
15:06Method 1.
15:08If ones are multiplied, 3 into 5 is equal to 15 ones.
15:1415 ones are equal to 1 ten plus 5 ones.
15:19If tens are multiplied, 3 into 1 is equal to 3 tens.
15:243 tens plus 1 ten are equal to 4 tens.
15:28Method 2.
15:30In method 2, 15 is split into 10 plus 5.
15:35Now multiply 10 plus 5 with 3.
15:38We get 3 into 5 plus 3 into 10 which gives 30 plus 15.
15:44Again now, 15 is split into 10 plus 5.
15:48Then we add 30 plus 10 which is equal to 40.
15:53Therefore, we have 40 plus 5 equal to 45.
15:57So, finally the answers of method 1 and method 2 are equal.
16:03That is 45.
16:16Here we are given 22 into 4.
16:20Where in 22, 2 is in ones place and 2 is in tens place.
16:26Method 1.
16:28If ones are multiplied, 2 into 4 is equal to 8.
16:338 is in ones place.
16:35If tens are multiplied, 2 into 4 is equal to 8 tens.
16:408 is in tens place.
16:43Method 2.
16:45In method 2, 22 is split into 20 plus 2.
16:50Now multiplying 20 plus 2 with 4.
16:55We get 4 into 2 plus 4 into 20 which gives 80 plus 8.
17:01Therefore, the answer is 88.
17:04So, finally the answers of method 1 and method 2 are equal.
17:10That is 88.
17:16Here we are given 45 into 5.
17:19Where in 45, 5 is in ones place and 4 is in tens place.
17:25Method 1.
17:27If ones are multiplied, 5 into 5 is equal to 25 ones.
17:3325 ones are equal to 2 tens plus 5 ones.
17:38If tens are multiplied, 5 into 4 is equal to 20 tens.
17:4320 tens plus 2 tens are equal to 22 tens.
17:48Therefore, the answer is 225.
17:51Method 2.
17:53In method 2, 45 is split into 40 plus 5.
17:58Now multiplying 40 plus 5 with 5.
18:02We get 5 into 5 plus 5 into 40 which gives 200 plus 25.
18:09Again now, 25 is split into 20 plus 5.
18:14Then we are adding 200 plus 20 which is equal to 220.
18:20Similarly, 220 plus 5 is equal to 225.
18:26So, finally the answer of method 1 and method 2 answer are equal.
18:32That is 225.
18:43Practice Zone.
19:05Try to solve the problems in the practice zone on your own.
19:14Summary.
19:18Let us recap the highlights of this chapter.
19:22When a number is multiplied with 0, we will always left with 0 irrespective of the number we are multiplying.
19:31We will always left with the same number which we have multiplied with 1 when the number is multiplied with 1.
19:40We use the symbol cross for multiplying the numbers.
19:44We have seen various methods to multiply the bigger numbers.
19:48We had a glance on equals of multiplication.
19:52We have learnt an easy multiplication when the things are arranged in the form of rows.
20:01Follow up work.
20:03Movie ticket for a child is rupees 10 and for an adult rupees 15.
20:08If a family spends rupees 100 for tickets, how many children and adults are there in the family?
20:15Multiply the numbers by splitting the place value.
20:1933 into 4.
20:21Direct multiplication using tables.
20:2446 into 3.
20:28Test your understanding of the chapter by taking the mock unit test.
20:38You have successfully completed the chapter multiplication.