Question

How do you evaluate `20+ 6\div 2\times 10- 5`?

Answer 1

The answer is `45`.

Explanation:

We use BODMAS to help simplify this. There are no Brackets and no Orders, so we go straight to Division and then Multiplication, before going on to Addition and then Subtraction. The direction is left to right.

`20+6-:2xx10-5`

There are no Brackets and nor Orders, so we go directly to Division.

There is one Division: `6-:2=3`

Hence:

`20+3xx10-5`

Next comes Multiplication: `3xx10=30`

Hence:

`20+30-5`

Next comes Addition: `20+30=50`

`50-5`

Last is Subtraction: `50-5=45`

`45`

Answer 2

`45`

Explanation:

When working with an expression that has different operations, start by counting the number of TERMS first. Terms are separated by PLUS and MINUS signs. Simplify each term to a final answer and these will be added or subtracted in the last step.

Within each term: do

• brackets first
• then powers and roots
• then multiplication and division

`" "color(red)(20)color(blue)(+6div 2xx10)color(green)(-5)" "larr` there are 3 terms

`=color(red)(20)color(blue)(+6div 2xx10)color(green)(-5)`
`color(white)(xxxxxxx)darr`
`=color(red)(20)color(blue)(" "+3xx10)color(green)(-5)`
`color(white)(xxxxxxxxx)darr`
`=color(red)(20)color(blue)(" "+30)color(green)(" "-5)`

`= 50-5`

`=45`