$5, 60$ plus 120, minus 100, plus 120, minus $100, \ldots \ldots$, each addition and subtraction is considered 1 operation. How many operations are required at least to get exactly 500? (Provided by Wang Xiaohan, Online School Teacher)
(A) 22
(B) 33
(C) 44
(D) 55
【Answer】B
【Analysis】It is easy to mistakenly choose answer C, as some children might simply understand it as adding 120 and then subtracting 100, resulting in a net increase of 20, thus $(500-60) \div(120-100) \times 2=44$ (times). In fact, this is a hidden snail climbing out of a well problem. If the last operation is adding 120, then the previous result is $500-120=380$, which involves $(380-60) \div(120-100) \times 2=32$ operations. Adding the final operation, it totals 33 operations.