Introduction to multiplication

0:00our squirrel friend here likes to collect acorns because really that's how he is able to live and let's say every day he collects exactly three acorns and so what i'm curious about is how many acorns will he have after doing this for five days so one way to think about it is every day he is able to collect a group of three acorns so you could view this as maybe what he's able to collect in day one and then in day two he's able to collect a second group of three acorns in day three he's able to collect another group of three acorns and every day is the equal number of acorns that he's collecting on the fourth day another three on the fifth day another three and so if you were curious how many total acorns he's

0:48collected well you could just count them up or you could think about well he's got five groups of three acorns five equal groups of three acorns so you could say five groups of three acorns three acorns and so the total amount would be five we could view this as five threes now five threes you could view this as five threes added together three plus three plus three plus three plus 3 and if you wanted to calculate this you could skip count by 3 so this would be 3 6 9 12 15 because we add 3 we get to 6 we add another 3 we get to 9 we add another three we get to 12 we add another three we get to 15. and so this would be a way of recognizing that you have 15 acorns but we're starting to touch on one of the most fundamental ideas in all of mathematics in fact we

1:53actually are applying it we just haven't used the word and that's we are multiplying we are using multiplication all multiplication is is this notion of multiple equal groups of something so here one way to express what we just did is we just when we said five threes that's the same thing as five and i'm going to introduce a new symbol to you five times three so all of these things are equivalent you're already used to seeing equal groups and multiple equal groups and you're used to adding something multiple times and you're used to skip counting and all of that is in some way shape or form you have been doing multiplication so when someone says 5 times 3 you could view that as 5 groups of 3 or you could view that as five threes or you could do that as three

2:51plus three plus three plus three or you could view that as fifteen i'll leave you there there's a lot of practice on khan academy to work through this and make sure you get the underlying idea but as you'll see this is perhaps one of the most useful concepts that you might learn in your entire lives