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21 multiple-choice questions and 30 flashcards on Adding and Subtracting Rational Numbers, about 14% of the 7th Math: The Number System bank. Every one carries a written rationale.
Adding and Subtracting Rational Numbers is one of 4 chapters in CoStudy's 7th Math: The Number System bank, and it holds 21 of the bank's 150 multiple-choice questions — roughly 14% of the total. That proportion is not arbitrary: chapters follow the certifying body's published exam outline, and the number of questions in each is set by that domain's published weight, so the share of your practice time this chapter takes matches the share of the real exam it accounts for.
Studying by chapter is worth doing once you have a diagnostic score. A single overall percentage tells you whether you are close; it does not tell you which domain is dragging. Working a weak chapter in isolation, and re-testing it in isolation, is the fastest way to move a score that has stalled — and it is why the mock exams in CoStudy report by domain rather than as one number.
10 questions drawn from this chapter, with the full rationale shown — the controlling principle behind the right answer, and why each wrong option tempts and fails.
Compute: 6.4 − 9.1
Answer: D — −2.7
D) 6.4 + (−9.1) = −2.7. A) Wrong direction. B/C) Magnitude error.
−7 + 4 =
Answer: C — −3
C) Net movement toward zero, ending at −3. B) Sign error. A) Added magnitudes. D) Added with wrong sign.
Convert −7/4 to a mixed number:
Answer: C — −1 3/4
C) 7/4 = 1 3/4; carry sign. B/D) Wrong remainder. A) Lost sign.
Compute: −2/5 + 3/10
Answer: C — −1/10
C) −4/10 + 3/10 = −1/10. A) Sign error. B/D) Added magnitudes.
Compute: (−5/6) + (1/2)
Answer: A — −1/3
A) −5/6 + 3/6 = −2/6 = −1/3. B) Sign. C/D) Different operation.
Convert −3 1/5 to an improper fraction:
Answer: D — −16/5
D) 3·5 + 1 = 16; keep sign. B) Sign. A/C) Arithmetic error.
Compute: −1.2 + 3.5
Answer: C — 2.3
C) 3.5 − 1.2 = 2.3, sign of 3.5. A) Sign error. B/D) Added magnitudes.
Compute: (−7/8) − (−1/4)
Answer: A — −5/8
A) −7/8 + 2/8 = −5/8. B) Sign. C/D) Treated minus-neg as minus.
Compute: 1/2 − 3/4
Answer: C — −1/4
C) 2/4 − 3/4 = −1/4. A) Subtracted wrong way. B/D) Sign or value error.
Compute: 0.25 + (−0.75)
Answer: D — −0.5
D) Different signs → −0.5. A/B) Added magnitudes. C) Sign.
4 cards from the 30 in this chapter.
What is 1/2 + (−1/4)?
1/4. (Common denom: 2/4 + (−1/4) = 1/4.)
What is −12 + 7?
−5.
What is −5 + (−6)?
−11. (Adding two negatives makes a more-negative result.)
What is 7 × (−8)?
−56.
These are a sample. The full Adding and Subtracting Rational Numbers chapter runs 51 items with per-chapter progress tracking, on the web and in the iOS app.
Open 7th Math: The Number System in CoStudy →