New posts in Recreational Mathematics

Is there a bijective, monotonically increasing, strictly concave function from the reals, to the reals?

Overlapping circles covering polygon

Distribution at First Time a Sum Reaches a Threshold

If $f(x)=\int_{x-1}^x f(s)ds$, is $f$ constant? Periodic?

Integral for the New Year $2019$!

New Year Maths $2019$

Numbers such that they equal the product of their own digits

Reverse engineering a math magic trick involving matrices.

Upside-down equation: algebra puzzle

How can I find integers which satisfy $\frac{150+n}{15+n}=m$?