Why multiplying float number by multiple of 10 seems to preserve better precision?
The only numbers that can be stored exactly are rational numbers whose denominator is a power of 2 (read any source on floating point numbers to understand why). For example, floating point numbers do satisfy
$$ 1/4 + 2/4 = 3/4 $$
but do not satisfy (or rather, don't necessarily satisfy)
$$ 1/3 + 2/3 = 3/3. $$
There's nothing magical about the number 10. It's just an artifact of the common decimal representation. So in general it won't help to multiply by a power of 10.