Video: Solving Word Problems by Dividing Whole Numbers by Unit Fractions

If 1/8 of a box of sweets contains 4 sweets, then the whole box contains _ sweets.

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Video Transcript

If one-eighth of a box of sweets contains four sweets, then the whole box contains what sweets.

In this problem, we need to calculate the total amount of sweets that are inside a box. And the only information we’re given is how many sweets there are in part of the box. To help us think about what we need to do to find the answer, we could sketch a bar model. We’re told that one-eighth of a box of sweets contains four sweets. We can show this on our bar model by drawing a bar to represent the whole box of sweets. Then dividing it up into eight equal parts to show eighths, and then finally labelling one of those eighths with the number four. One-eighth of a box of sweets contains four sweets.

So how can we calculate the number of sweets in the whole box? We know that eight-eighths are the same as one whole. And so if one-eighth of our box contains four sweets, then to find out the number of sweets in the whole box, we need to multiply to find eight lots of four. A fact that can help us is 10 fours are 40. So eight fours are going to be two less fours than 40 or eight less than 40. And if we subtract eight from 40, we’re left with 32. If one-eighth of a box of sweets contains four sweets, then the whole box contains 32 sweets. The answer is 32.

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