



 
Hi Jeff, Compatible numbers are not well defined things. The idea with compatible numbers is to replace the numbers in the problem with numbers that are approximately the same and yet the calculations are easy. In this problem what I think is expected is to replace 9.4 with 10 and 62.6 with 60 giving an approximate sum of 10 + 60 = 70. Rounding has a more precise definition. If you are rounding to an integer then 9.4 rounds to 9 and 62.6 to 67. This gives an approximate sum of 9 + 63 = 72. Harley  


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