Question 206593
let x = the width of the grid.
{{{x^2 +24}}} = the number of characters
{{{(x+1)^2 -25}}} = the number of characters.
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You can solve this algebraically, or using properties of squares, which is faster.
For any two numbers {{{a}}} and {{{b}}} such that {{{a+1 = b}}}, {{{b^2-a^2=a+b}}}
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Here we have {{{x^2+24=(x+1)^2-25}}}
{{{24+25 = (x+1)^2-x^2}}}, which matches the difference of two squares above.
So, x=24 and x+1 = 25.
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To find the number of characters, use either value in the equations obtained at the start.
{{{x^2 +24}}} = the number of characters
= {{{24^2 + 24}}}
= {{{576 + 24}}}
=600