In Python and JavaScript, 0.1 + 0.2 is not equal to 0.3. In Raku it is, because 0.1 is stored as a fraction.
Most programming languages cannot add 0.1 and 0.2 exactly. Raku can, and that surprises people who already know the other answer.
In Python
print(0.1 + 0.2 == 0.3)
print(0.1 + 0.2)False 0.30000000000000004
In JavaScript
console.log(0.1 + 0.2 === 0.3);
console.log(0.1 + 0.2);false 0.30000000000000004
In Raku
say 0.1 + 0.2 == 0.3; say 0.1 + 0.2;
True 0.3
This is not say rounding the result for you. The sum really is three tenths.
Why
Python and JavaScript store 0.1 as a binary floating-point number. One tenth has no exact form in binary, in the same way that one third has no exact form in decimal: 0.3333… never ends. So the computer stores the nearest value it can. The small errors in 0.1 and 0.2 add up, and the sum misses 0.3 by a tiny amount.
In Raku, a number written with a decimal point, like 0.1, is a Rat, a rational number. It is stored as two integers: a numerator and a denominator. 0.1 is 1/10, 0.2 is 2/10, and their sum is 3/10, exactly. The method .nude shows the two integers; its name comes from numerator and denominator.
say 0.1.WHAT; say 0.1.nude; say (0.1 + 0.2).nude;
(Rat) (1 10) (3 10)
The same goes for division: 1/3 is kept as one third, not as 0.333333, so three of them make exactly one.
say 1/3 + 1/3 + 1/3 == 1;
True
Say it in Raku
There is nothing to fix. Decimal numbers in your program add up the way they do on paper.
When you do want a floating-point number, for speed or to get the same result as another language, write it with an exponent: e0 means “times ten to the power of zero”. Then Raku gives the same answer as Python.
say 0.1e0 + 0.2e0 == 0.3e0; say 0.1e0 + 0.2e0; say (0.1e0 + 0.2e0).WHAT;
False 0.30000000000000004 (Num)