Step by step
The question
Question: find the value of 10 − 2n when n = 3.
10 − 2n
n = 3
1 Put the numbers in
We put 3 in place of n.
2n means 2 times n.
So we write a times sign.
= 10 − 2 × 3
2n = 2 × n
2 Times and divide
Times comes before minus.
Order: ( ) → x² √ → × ÷ → + −
2 times 3 is 6.
= 10 − 6
3 Plus and minus
10 minus 6 is 4.
= 4
Careful!
Many people go from left to right and get 24.
But times and divide come before plus and minus.
Careful: not 10 − 2 × 3 = 24 ✗
So 10 − 2n is 4 when n = 3.
Let's look back.
First: put the numbers in.
Then: times and divide.
Last: plus and minus.
Answer
= 4