MB 89F Standard Calculator

MB-89F is a calculator that can think in exact fractions. Note: this is a standard format calculator with a normal equals key. If you are looking for the RPN version of the calculator, please download the MB-88F version, which utilizes Reverse Polish Notation. Every value is kept as a whole-number numerator over a whole-number denominator, so the math never drifts. 1/3 + 1/6 is exactly 1/2, never 0.4999. Whether you're cutting a board, scaling a recipe, piecing a quilt, or checking fraction homework, the answer stays exact — and inches and millimeters relate by the exact definition 1 in = 25.4 mm, so conversions never lose a thousandth. HOW IT WORKS You key a calculation the natural way and press equals. To compute 3/4 + 1/2: key 3 b/c 4, press +, key 1 b/c 2, then press = — the answer 1 1/4 appears. No RPN to learn, no notation to juggle. Operations chain left to right, and pressing = again repeats the last one. A built-in manual, key index, and cheat sheet are right there if you need them. WHAT IT DOES • Exact fraction arithmetic — add, subtract, multiply, divide, always reduced to lowest terms • Mixed-number entry: key 2 SPC 1 b/c 2 for 2 1/2 • Tape-measure rounding to 1/8, 1/16, 1/32, or 1/64 — and TRU to restore the exact value • Fraction ↔ decimal conversion both ways • Exact unit tagging and conversion: inches, feet, millimeters, meters • Feet read as feet plus fractional inches (22.5 ft → 22 ft 6 in) POWER KEYS • 1/x, x², and √x for diagonals and right-triangle math • ½x to instantly find a centerline, 2x to double it • Store/recall memory (STO/RCL) to hold and reuse a value • History tape — tap the display to see your last 100 results and bring any of them back with a tap MADE TO LIVE WHERE YOU WORK • Universal — one app, built for both iPhone and iPad • Your value, memory, and history are saved between sessions — pick up right where you left off • 11 color themes • Optional thousands separator and fixed decimal places • Built-in user manual, key index, and cheat sheet • Works 100% offline. No account, no ads, no tracking, no data collected — ever. Try it free for 2 days, then unlock the full app forever with a single one-time purchase — no subscription. Woodworkers, machinists, carpenters, and framers rely on it — and so do quilters and sewists, cooks scaling recipes, students working through fraction homework, and anyone who'd simply rather see 3/4 than 0.75. If you think in fractions, MB 89F keeps them exact.