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grade8_integers_quiz3 draws its questions at random from a bank of 10 questions, with full worked solutions for every one.
A few of the question types, with full solutions, so you know what to expect.
A submarine is 25 metres below sea level. Which integer represents this depth?
Answer: -25
\(\text{Sea level is the reference point, taken as } 0.\)
\(\text{Below sea level is represented by a negative integer.}\)
Which of these statements is TRUE?
Answer: \(-5 > -12\)
\(\text{On a number line, moving right means increasing.}\)
\(-5\) \(\text{is further right than}\) \(-12\text{, even though 12 is numerically larger than 5.}\)
Calculate: \((-8)+(-11)\)
\(\text{Same signs: add the values and keep the sign.}\)
\(8 + 11 = 19\)
Calculate: \(250-(-40)+(-75)\)
Answer: 215
\(\text{Rewrite subtracting a negative as adding a positive: } 250+40-75\)
\(250+40 = 290\)
\(290-75 = 215\)
*Always rewrite double signs before calculating, to avoid sign errors.
Estimate the sign and size of: \(-2998 \times 51\)
Answer: Negative, about 150 000
\(\text{Estimate using rounded numbers: } -3000 \times 50\)
\(3000 \times 50 = 150\,000\)
\(\text{Signs differ (negative and positive), so the answer is negative.}\)