You can call it whatever you want, as long as it equals 1/2 it's the same number.

So yes, multiplying by 2/2 to make it more intuitively obvious is perfectly valid and a good way to think about it. Most arithmetic tricks are ultimately multiplying by 1 or adding 0 just to make the problem easier to handle.

I think it's easier to picture it in terms of fractions. When you divide by a fraction, you reciprocate the divisor. That is, you flip its numerator and denominator, then multiply them. In this case, we're taking 1/4 and dividing it by 1/2. You take the reciprocal of 1/2, which is 2/1. Then multiply the numerators and denominators. You end up with (1/4)*(2/1)=2/4=1/2=0.5

0.25 is half of 0.5. Alternatively: A quarter is half of half. If you multiplied 0.25/0.5 by 2, then it would be 0.5/1, which is just 0.5.

Huh, that's a cool way to think of it. I've done a decent amount of higher level maths but stuff like this always cooks my brain if I let it. I thought of the numbers as the fractions 1/4 and 1/2, which then reminds me that 1/2 * 1/2 = 1/4, but I think your way feels more elegant