Answer:
Step-by-step explanation:
Yes bill is correct because both numbers are easy to add without regrouping, since when each of the digit are added there won't be carried over. Also, I believe Bill should be able to do simple mathematics like 2+3, 3+5 and so on.
Then, he should be able to add 3 plus 0 in his head and keep the result as 3. And then add the other 2+4 and he will put the two result together as 63
