Question

How do you simplify `21 - 1 times 2 ÷ 4` using order of operations?

Answer 1

20.5

Explanation:

What you need to remember when solving this is the following:

you start by looking if there are any parenthesis, because you need to solve whatever is between the parenthesis before doing anything else. Inside the parenthesis the same rules apply as discussed here.

Then you look if there are any exponents, they need to be solved after you solved the parenthesis.

When you have done that you multiply or divide if necessary. It doesn't matter in which order so you can go from left to right or from right to left with multiplying or dividing, whatever suits you best.

Finally you add or subtract. Just like with multiplying or dividing, it doesn't matter which order you choose.

So with the equation `21 - 1 * 2 ÷ 4` you see that there are no parenthesis or exponents, but you can divide and multiply.

Which leaves you with `21 - 2 : 4 = 21 - 0.5`

Then you are left with a subtraction, which you can solve as `21 - 0.5 = 20.5`