$x = 0;
$x += 0.1 for 1..10;
$x_eq_1 = $x == 1 ? 'yes' : 'no';
print("$x = 1? $x_eq_1\n");
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1 = 1? no
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Some numbers can't be represented by floats. Your print statement is rounding the number. This include numbers that are periodic in binary. 0.1 is one of them.

...
printf("\$x is really %.16e\n", $x);
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...
$x is really 9.9999999999999989e-001
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If you print your numbers using %.16e, you'll find at least one isn't what you think it is. You should never check floats for equality.