How to see it
A letter stands for a number we do not know, or one that can change. When a number sits next to a letter, it means multiply. Three n is three times n. Write a times a as a squared, and leave out the times sign. N plus 5 means five more than n.
A worked example
3n plus 2 when n is 4. Put the 4 in the box: 3 times 4 is 12, plus 2 is 14.
The common mistake: putting the number next to the letter instead of multiplying
The trap is writing 3n as 34, as if the digits sit side by side. In algebra, side by side means times. Also a squared with a equal to 3 is 9, not 6.
Try one
5a take away 3, when a is 6.
- A27
- B53
- C33
- D3
Show the answerHide the answer
Right: A, 27
5 times 6 is 30, take away 3.