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1/2" + 13/16"

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

1/2" + 13/16" =
=1-5/16"
Sum
1-5/16"
Decimal inch
1.3125"
Millimetres
33.3375 mm
1/2" − 13/16"
-0-5/16"
The work

Over a common denominator

Put both over 16: 1/2 = 8/16 and 13/16 = 13/16. Add the tops: 8/16 + 13/16 = 21/16, which carries past one inch. Reduced, that's 1-5/16" (1.3125 inches). TapeMath tracks it as an exact fraction, so it lands dead on the tape mark.
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