Answer:
1
Explanation:
4.34 + 5.66 = 10
number of significant figures in 10: 1
(the significant figure here is 1)
here's a clear explanation from Northern Kentucky University (NKU)
[To determine the number of significant figures in a number use the following 3 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
Example: .500 or .632000 the zeros are significant
.006 or .000968 the zeros are NOT significant ]
[For addition and subtraction use the following rules:
Count the number of significant figures in the decimal portion ONLY of each number in the problem
Add or subtract in the normal fashion
Your final answer may have no more significant figures to the right of the decimal than the LEAST number of significant figures in any number in the problem.]
(https://www.nku.edu/~intsci/sci110/worksheets/rules_for_significant_figures.html#:~:text=To%20determine%20the%20number%20of,decimal%20portion%20ONLY%20are%20significant)