Question

How do you solve `3.15\div 0.45`?

Answer 1

`7`

Explanation:

The first step is to convert the 2 decimal numbers into whole numbers.
This is achieved by `color(blue)"multiplying both numbers by 100"`

`rArr3.15÷0.45=3.15/0.45larr" in fractional form"`

`=(3.15xx100)/(0.45xx100)=315/45larr" whole numbers"`

We can now `color(blue)"cancel"` these numbers by dividing both by the same `color(blue)"common factor"`

Since both numbers have a last digit of `color(red)(5)` this means that they are divisible by 5.

`rArr(315÷5)/(45÷5)=63/9=7larr" if you know 9 times table"`

This is usually written as: `cancel(63)^7/cancel(9)^1=7`

Otherwise repeat the process, using a factor of `color(red)(3)`

`rArr63/9=cancel(63)^(21)/cancel(9)^3=21/3=7larr" 3 times table"`