I have been studying about significant digits and addition rules and I can't quite digest the rules of addition completely.
It states that in the answer number of decimal places will be equal to the least number of decimal places in the terms. $//$What my teacher has taught me and what my book says
This makes sense first :
If we had went for number of significant digits rule we would have retained only $3$ significant digits.
But consider this case :
The number of significant digits in both of initial terms were $1$ and $2$ respectively, but in the final answer they are $4$. There are more significant digits in the answer. Isn't it wrong as last three digits of $1.10^3$ are insignificant
Please clear my doubt or whether the rule has an extension.
EDIT $1000$ changed to $1.10^3$. I don't think anyone understands what am I asking. I $know$ what the rules are and how to apply them but I want to know that $1.10^6+1.0=1000001$ . Don't $you$ think it is wrong as we are not sure of second last digit of $1.10^6$ but we are of $1000001$