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Video: Addition & Subtraction of Fractions With Whole Numbers

Video Transcript

Hi, my name is Marija and I'm a mathematician and today I'm going to teach you about addition and subtraction of fractions with whole numbers. So if we've got the whole number 3 and we want to add to it 2/3, here's all you have to do. You take the whole number and you write it first and you take the fraction and you write it right next to it. And your answer is just 3 2/3. So if I want to add the whole number 3 plus the fraction 2/3, I just write 3 2/3. Subtraction is a little more difficult. So lets say we want to do 3 minus 2/3, well first I have to have the denominators the same alright? So I want to rewrite 3 as a number that has 3 as the denominator. So think about what number divided by 3 is 3. That number is 9. So I'm going to rewrite 3 as 9/3 - 2/3. Okay, now that my denominator is the same I can go ahead and keep the denominator and just deal with the numerators. So I'm doing 9-2=7. So my difference would be 7/3, but if your teacher wants you to write that as a mixed number then we're going to do this. See how many times 3 goes into 7. It goes in twice right? 3x2=6. That means that there is 1 left over so I'm going to write the remainder in the numerator over, keep the denominator. So it's 7/3 or 2 1/3. And that is how you add and subtract fractions with whole numbers.

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