How old am I? Poster
How Old Am I? Poster
Age
14 to 16
Challenge level
Problem
This poster is based on the problem How Old Am I?.
The poster is available as a PDF, or the image below can be clicked on to enlarge it.
Student Solutions
21
Why?
Image
Adding 30 to the age 15 years ago is the same as squaring it
| Number | Square | Difference |
|---|---|---|
| 3 | 9 | 6 |
| 4 | 16 | 12 |
| 5 | 25 | 20 |
| 6 | 36 | 30 |
| 7 | 49 | 42 |
The difference keeps getting bigger so 6 is the only solution
I was 6 15 years ago, so now I am 21