Multiplication I - How to Multiply Fractions With Whole Numbers
There is a delicious recipe for cookies. You take:
- 3 parts flour
- 2 parts butter
- 1 part sugar
That's a total of 6 parts. So:
^{3}/_{6} of flour, ^{2}/_{6} of butter and ^{1}/_{6} of sugar
If you want to make 300g of dough, that is:
Flour: | ^{3}/_{6} of 300g |
Butter: | ^{2}/_{6} of 300g |
Sugar: | ^{1}/_{6} of 300g |
Formula: Multiply Fractions and Whole Numbers
If you write "any fraction of something", it always means that you have to multiply these two numbers with each other.
A fraction is multiplied by a whole number by multiplying the numerator by the whole number and keeping the denominator.
The result often can be simplified / reduced:
For example the fraction ^{5}/_{12} should be multiplied by 18:
Trick: Simplify the Fraction or Whole Number BEFORE multiplying!
Before multiplying the fraction by the whole number, first check whether you can simplify the fraction. This reduces the numbers and makes the multiplication easier.
The whole number may also be simplified with the denominator of the fraction.
If you have simplified as much as possible before multiplying the fraction with the whole number, the result cannot be further simplified.
Multiplying Fractions and Whole Numbers
Now we can continue to bake our cookies. The list of ingredients:
Flour: ^{3}/_{6} of 300g = ^{3}/_{6} × 300g = ^{1}/_{2} × 300g = ^{1}/_{1} × 150g = 150g |
Butter: ^{2}/_{6} of 300g = ^{2}/_{6} × 300g = ^{1}/_{3} × 300g = ^{1}/_{1} × 100g = 100g |
Sugar: ^{1}/_{6} of 300g = ^{1}/_{6} × 300g = ^{1}/_{1} × 50g = 50g |
Add another breeze of salt and mix well. Then shape the biscuits as desired and place them in the oven at 180°C for about 15 minutes. Tasty!