Video: Comparing Numbers Involving Multiplication of Numbers up to 999

A boy has 89 pounds. Can he buy 7 pens if each one costs 14 pounds?

02:18

Video Transcript

A boy has 89 pounds. Can he buy seven pens if each one costs 14 pounds?

Let’s sketch a bar model to help us understand what this problem is asking us? Let’s split this bar into seven equal parts. These can represent the seven pens that the question is talking about. The question also tells us the cost of each pen. Can he buy seven pens if each one costs 14 pounds? So we can label each part as being worth 14. Now, the total of our bar model can be calculated if we can work out what this value is here. In other words, what’s seven lots of 14. And the question tells us about a boy. And we’re told that he has 89 pounds. But can he afford the seven pens?

Well, the only way we can work out the answer is to calculate what seven times 14 is and then compare this with 89 pounds to see if he has enough money. So let’s start by working out the multiplication. How can we work out seven times 14? Well, we can start by partitioning 14 to help us. We could break it down into 10 and four. 10 and four makes 14. Seven times 10 equals 70. We know that seven times two is 14. So it’s seven times double two, which is four, is double 14. The answer is 28. Now, let’s combine our two parts back together again to find the answer to the multiplication. 70 plus 28 equals 98. And so, we can say that seven times 14 equals 98.

Let’s get back to our problem. A boy has 89 pounds. And we’ve now worked out that the cost of seven pens is 98 pounds. 89 is less than 98. So can the boy buy seven pens if each one costs 14 pounds? Unfortunately, the answer is no.

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