Select a range and answer the square number quiz.
Click 'Check' to see if you're correct.
Max must be at least as large as Min.
Min and Max are 1 and 99 by default.
Negative values are treated as 1.
This program helps people remember square numbers through interactive quizes.
Why bother? If you remember square numbers, you can reduce multiplication into at most two addition and subtraction via $a^2-b^2 = (a+b)(a-b)$. For example, $$\begin{align} 37 × 21 & = (29+8)(29-8) \\ & = 841-64 \\ & = 777 \end{align}$$ and $$\begin{align} & 98 × 19 \\ = & 19 + 97 × 19 \\ = & 19 + (58+39)(58-39) \\ = & 19+3364-1521 \\ = & 19 + 1843 \\ = & 1862. \end{align}$$ Maybe, there are more merits.