Mistake Master
Right value, right form, full field
A quarter of the math section has no choices to lean on: you type the answer, and the field grades characters, not intentions. A mixed number silently becomes a different value, a truncated repeater scores zero, a dropped sign flips the answer. The rules are few and mechanical, which is exactly why they are worth ten minutes once and zero losses forever.
§1
What this topic is about
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About a quarter of SAT Math questions have no answer choices: you type the value. The math can be perfect and the point still lost at the keyboard. This topic covers the entry rules that matter: form (no mixed numbers, no symbols, signs included) and precision (fill repeating decimals, never truncate exact ones, and stop worrying about reducing).
§2
No mixed numbers, ever
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The entry field reads characters, not spacing. A mixed number like $3\dfrac{1}{2}$ typed as "3 1/2" is read as $\dfrac{31}{2}$, fifteen and a half, silently wrong.
- Convert mixed numbers before entering: $3\dfrac{1}{2}$ goes in as $7/2$ or $3.5$.
- The improper fraction is always safe; the decimal is safe when it terminates.
- Watch scratch paper habits: the mixed form is fine to WRITE, never to TYPE.
Worked example. A computation gives $2\dfrac{3}{4}$ hours. What gets typed?
$2\dfrac{3}{4} = \dfrac{11}{4} = 2.75$.
"2 3/4" cannot be entered; "23/4" reads as $5.75$; "2.34" mashes digits. Only $11/4$ or $2.75$ scores.
§3
Numbers only: symbols stay outside
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The question names the units; the field takes a bare number. Dollar signs, percent signs, and unit words have no keys, and converting to different units than asked changes the value.
- "How many dollars" plus an answer of $\$40$ means typing $40$.
- "What percent" plus an answer of $45\%$ means typing $45$, not $0.45$.
- Negative signs DO go in; the sign is part of the value, not a symbol.
Worked example. $27$ of $60$ students chose the museum. What percent gets typed?
$\dfrac{27}{60} = 45\%$.
$45$. Typing $0.45$ answers in decimal-share units the question did not ask for.
§4
Fill the field
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Repeating decimals must fill the entry length or be dodged entirely by typing the fraction. Exact decimals must go in whole. And fractions never need reducing when they fit.
- $\dfrac{2}{3}$: type $2/3$, $.666$, or $.667$. Never $.67$, $.66$, or $.7$.
- $\dfrac{5}{8} = .625$ exactly: all three digits go in.
- $\dfrac{4}{6}$ scores as-is; reduction is optional, always.
Worked example. The answer is $\dfrac{5}{6}$. Which entries score?
$5/6$ types cleanly and skips the decimal question entirely.
$.833$ scores; $.83$ and $.8$ stop short and do not. When a decimal repeats, the fraction is the calmer entry.
§5
A ten-second protocol
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Before typing: is it a mixed number (convert), does it carry a symbol (drop it), is it negative (keep the sign), does it repeat (prefer the fraction)? Four questions, ten seconds, zero mechanics losses.
Convert mixed numbers to improper fractions or decimals, type bare numbers in the asked units with signs intact, fill repeating decimals or dodge them with the fraction, and never spend time reducing.
§6
Two patterns that cost real points
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Two patterns cover this topic. They are the same ones the diagnostic routes on.
The right value goes in wearing the wrong form.
A mixed number gets mashed into a different value, a $ or % symbol tries to enter, or the negative sign gets left on scratch paper.
Fix. Convert mixed numbers before the field, drop every symbol (the question's units govern), and carry the sign in; it is part of the value.
The right value goes in at the wrong precision.
A repeating decimal stops at two digits, an exact decimal gets rounded, or time burns on reducing a fraction that already scores.
Fix. Fill the field or type the fraction. When the decimal repeats, the fraction entry is exact, faster, and immune to rounding judgment calls.
Ten quick checks across the two patterns: mixed-number conversion, symbol-free entries in the asked units, signs carried in, repeaters filled or dodged, and exact decimals entered whole. Pick or type your answer, then check. Progress is saved.