Nagwa uses cookies to ensure you get the best experience on our website. Learn more about our Privacy Policy.

Video: Multiplying Two Numbers Using the Distributive Property of Multiplication

Tim Burnham

You are told that 39 × 7 = 273 and 39 × 30 = 1170. Use this to find 39 × 37.

02:17

Video Transcript

You’re told that thirty-nine times seven equals two hundred and seventy-three and thirty-nine times thirty equals one thousand one hundred and seventy. Use this to find thirty-nine times thirty-seven. Well in finding thirty-nine times thirty-seven, you’ll notice in the information we were given we’ve got thirty-nine times seven and we’ve got thirty-nine times thirty. So that thirty-nine is common to all of those. Now thirty-seven can be got by adding seven and thirty. So let’s write a few things down

Thirty-seven, as we’ve just said, is equal to seven plus thirty. So we can rewrite thirty-nine times thirty-seven as thirty-nine times seven plus thirty. Now we can use the distributive property of multiplication, and thirty-nine times seven plus thirty means thirty-nine times seven plus thirty-nine times thirty. And we were told in the question that thirty-nine times seven is equal to two hundred and seventy-three and thirty-nine times thirty is one thousand one hundred and seventy. So we can replace these in our calculation, which means that thirty-nine times thirty-seven is simply two hundred and seventy-three plus one thousand one hundred and seventy.

And we can quickly do that addition, so three plus zero is three. Seven and seven is fourteen, so that’s four carry one. Two and one is three plus the one we’ve carried makes four. And just one on its own is one, so the answer is one thousand four hundred and forty-three. And there’s our answer then, thirty-nine times thirty-seven equals one thousand four hundred and forty-three. But in this case, actually the answer isn’t the main point of this. The question said use this, so use the fact that thirty-nine times seven is two hundred and seventy-three and thirty-nine times thirty equals one thousand one hundred and seventy in order to find that. So the important part is our calculation here specifically this bit here showing that you’re using the distributive property to complete that calculation. And if you wanted to be absolutely sure of doing the best possible working out, you might actually write down that you were using the distributive property of multiplication in your working out.