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9/16" + 15/16"

Adding two fractions of an inch, exactly — the everyday jobsite arithmetic that a decimal calculator gets wrong. Reduced, carried, and shown in millimetres.

9/16" + 15/16" =
=1-1/2"
Sum
1-1/2"
Decimal inch
1.5"
Millimetres
38.1 mm
9/16" − 15/16"
-0-3/8"
The work

Over a common denominator

Put both over 16: 9/16 = 9/16 and 15/16 = 15/16. Add the tops: 9/16 + 15/16 = 24/16, which carries past one inch. Reduced, that's 1-1/2" (1.5 inches). TapeMath tracks it as an exact fraction, so it lands dead on the tape mark.
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