Students in class 7 in a reputed school were given this project: write as many numbers as possible (0, 1, 2, 3…) using four 4s and any operations that the student knows. (+, – , * and / are surely allowed. Decimal points, exponents, square roots, etc can be used too, if the student knows them.
0 = 4 + 4 – 4 -4 (also, 44-44) (there could be more)
1 = 44/44
2 = 4/4 + 4/4
3 = (4+4+4)/4
11 = (4/.4) + 4/4
and so on. The only condition is that four 4s should be used – nothing more, nothing less!
Your child may find some big numbers easily doable (like 45 = 44+4/4) but he may be stuck with some small numbers (like 13 = 44/4 + sqrt 4 – for this he should know square root).
An easy option here is to Google for results on ‘four 4s’. You would come across many sites giving out the answer, including Wikipedia. But this is actually a pitfall. Resist handing out your child the solutions. Let him discover a few by himself.
Can you raise the bar here? Well, you could, by asking him to check if there is more than one solution for a number – for e.g., 3 = (4 + 4 +4)/ 4 as well as (4*4) – 4 / 4. Can any number other than 4 lend itself to such a possibility? Who knows, these questions might awaken the Ramanujan inside your child!