How to Do Fractions on a TI-84 Plus (▸Frac and the Fraction/Decimal Toggle)

A TI-84 always computes in decimal internally — there’s no separate “fraction mode” doing exact rational arithmetic under the hood. What you’re actually asking for when you “do a fraction” is a conversion: take the decimal answer you already have and display it as the simplest fraction that matches it.

The ▸Frac conversion

On the physical calculator, this is MATH → 1: ▸Frac, applied after you’ve evaluated an expression. Type 0.75, hit Enter, then MATH → ▸Frac → Enter, and 0.75 becomes 3/4.

The conversion works by finding the simplest fraction whose decimal value is close enough to your result to be indistinguishable given the display’s precision — which is why it can turn a repeating decimal like 0.3333333333 into the clean 1/3 it almost certainly came from.

Why some decimals won’t convert

If a decimal doesn’t come from a “nice” fraction — most irrational results like √2 or π, or a value with a denominator larger than the calculator’s search limit — ▸Frac either returns the original decimal unchanged or a fraction so large it’s not useful. That’s expected behavior, not a bug: some numbers genuinely aren’t close to any simple fraction.

Try it yourself

The TI-84 Calculator keeps a DEC/FRAC toggle right in the mode strip above the display — tap it once and every result switches to its fraction form automatically, no separate menu step required. It uses the same continued-fraction approach as the real ▸Frac, so sqrt(9)/4 still comes out as 3/4 instantly.