Question 1065783
This is a little tricky.   Say he's just watching the storage area for 45 minutes, does he check it once or twice?   I'll assume he checks it twice (at the very beginning and at the very end of the 45 minutes).
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9hrs is  9hrs*60min/hr = 540minutes.   540minutes/45minutes/check = 12

However, since 540/45 is exactly 12,  he will check it one more time at the very end, so {{{ highlight( 13 )}}} checks in all.

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The expression I am using is  {{{ number_of_checks = floor(number_of_minutes_in_shift / 45) + 1 }}}
    Where floor(n) = largest integer <= n