Rooting out and expunging critical thinking/thinkers is essential to maintaining a society that's wholly dependent on an authority to define what are facts and what is reality.

Even when the US public education system was more oriented toward teaching the three "R's", there was heavy emphasis on arriving at the correct answers via prescribed and approved methods where unorthodox steps would often invalidate the results.

For example, adding a series of not round numbers (say,113+874+988=?) necessitated the student who was asked to demonstrate his work, to specifically add the rightmost (1's) column of digits of the respective addends and carrying the extra digit (excess of 10) over and adding to the next (10's) column then likewise totaling that to a sum and treating likewise appending extra digits to 100's and so on depending on the numbers being added. You had to total the 3, 4, and 8 to get 15. "5" becomes part of the solution below the line and "1" is carried and added to the next column of 1, 7, and 8, to get 17. "7" is written to the left of 5 and the 1 is added to the 1, 8, and 9 to get 19; with no more addend digits above the line, the approved method validates the correct answer.

 113
 874
+988         
______
1975

A less onerous method would simply to be converting not-round numbers to the nearest round number plusor minus the difference then do simpler math.
113 becomes 100+13 874 becomes 900-26 and 988 becomes 1000-12

100
+900
+1000
______
2000

and

13
-26
-12
______
-25

then

2000
-25
______
975

The second method wouldn't pass muster with all math teachers because one did not use the accepted and taught method of arriving at the correct answer- even if the alternative way could be mathematically validated.

If you didn't follow instructions your correct answer would be marked as incorrect. This type of "instruction" rewards those who are more heavily dependent on an authority to guide thinking and reasoning.