If n is a positive integer, which of the following is a possible value of |56 - 5n|?

A. 7

B. 9

C. 12

D. 15

E. 20

The units place of 5n will either be 5 or 0.

The units place of 56 is always 6.

So; the possible values for units place of |56-5n| are:

6: 6-0=6 {for all 5n where units place of 5n is 0 and 5n<56 or n<12}

1: 6-5=1 {for all 5n where units place of 5n is 5 and 5n<56 or n<12}

9: 5-6=15-6=9 {for all 5n where where units place of 5n is 5 and 5n>56 or n>=12}

4: 0-6=10-6=4 {for all 5n where where units place of 5n is 0 and 5n>56 or n>=12}

Only number with above criteria is 9.

Ans: "B"

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~fluke

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