MB-88F Fractional Calculator

Exact fractions — never a rounded-off 0.4999. For the shop, the kitchen, the sewing table, or homework, with the RPN precision engineers swear by.

MB 88F is a calculator that thinks in exact fractions.

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.

NEW TO RPN? MB 88F uses Reverse Polish Notation: you key the numbers first, then the operation — 3, ENTER, 4, + instead of 3 + 4 =. No equals key, no parentheses to juggle. It's the input style engineers and HP-calculator fans have sworn by for decades because it makes real calculations flow. If it's new to you, it clicks in about a minute, and a built-in manual, key index, and cheat sheet are right there to walk you through it.

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 pull any of them back into the stack • Last-X recall, stack roll, and swap

MADE TO LIVE WHERE YOU WORK • Universal — one app, built for both iPhone and iPad • Your stack, 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 88F keeps them exact.