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Current time:0:00Total duration:4:42

Multiplication in real world contexts

CCSS.Math:

Video transcript

we are told there are 10 students in the Poetry Club this week each student wrote two poems what does the expression 10 times 2 represent and they give us some choices pause this video and see if you can work that out alright so there are 10 students in the Poetry Club and each student wrote two poems so I would use ten times two to figure out hey for each of those ten students if they each wrote two poems then we have ten times two total poems and if we look at the choices that is choice C right over here if we look at choice a the number of students the number of students is ten it wouldn't be ten times two and then the number of poems each student wrote well that's the second piece of information they each wrote two poems that wouldn't be ten times two either let's do another one of these a little bit different this time so now we're asked let me scroll this over a little bit which problem can we solve with three times eight so pause this video and have a go at it before we do it together all right now let's read these and see if you can solve it with three times eight Ellen has eight pieces of gum fair enough she ate three pieces at school I hope you didn't swallow the gum that that can be problematic how many pieces of gum does Ellen have left so would you use multiplication for that the way I would tackle it she has eight pieces of gum and if she ate three and we want to figure out how much gum that she have left I'm assuming outside of her body well then I would subtract three from eight I wouldn't multiply 8 by 3 so I would rule this one out that's not going to be my choice I'm not going to solve this problem with multiplication or at least by three times eight Brendon has eight t-shirts fair enough that's about how many I have he goes to the store to buy three more t-shirts how many t-shirts does he have now well I solved that with multiplication let's see the way I would solve it is he has eight shirts and then he's buying three more I would add three to figure out how many total t-shirts he has I wouldn't multiply by three so I'd rule that out so let's see how choice C is looking they're eight chocolates in each box Mike has three boxes of chocolates how many chocolates are there so this is interesting so he has three boxes of chocolates so let me draw those boxes one box two box three boxes of chocolate and each of them have ate chocolates one two three four five six seven eight one two three four five six seven eight one two three four five six seven eight well yeah if I want to figure out how many total chocolates there are I have three groups of eight I would solve that by multiplying 3 times 8 so I like this choice a lot let's do another example here we are told Gerald is going to plant a garden this spring that's a good thing to be doing he plans to have 7 plants in each row there will be 8 rows which expression can Gerald use to find the total number of plants needed for his garden pause this video and see if you can figure that out alright I'll do a little bit of a drawing I'll do it in green because we're talking about rows of plants so 7 plants in each row and there will be 8 rows so 1 2 3 4 5 6 7 7 plants in each row and then we're going to have 8 rows so let me copy and paste that so so that's 2 rows that's 3 rows that is 4 rows again there 5 rows 6 rows [Music] 7 rows and 8 rows so we don't have to actually calculate it but the way you could think about it is you have 7 plants in each row and then you have 8 rows of plants 8 rows of plants so if you want to figure out the total amount you would multiply 8 times seven and so let's see that's this first choice right over here you wouldn't multiply 8 times 7 times 7 and 8 plus 7 is definitely not going to give you the total number of plants here so yeah we like using the 8 times 7 and we're done