Explanation:
a=5( all of them)
b=5 (The last 5, the first two zeroes don't count)
c=2 ( The first two numbers)
Rules:
Non-zero digits are always significant
Any zeros between two significant digits are significant
A final zero or trailing zeros in the decimal portion ONLY are significant
If the zeroes are before a decimal but not in between two significant numbers, they are not significant