Expresswala Academy Mathematics Tuition

Cubes and Cube Roots

MCQ test, Set 4

  • Set 4 of 10
  • 25 questions
  • 25 marks
  • 30 minutes

Download the PDF (with key sheet and solutions, 75.1 KB)

Choose one answer for each question, then check your score at the end. Each correct answer carries 1 mark; there is no negative marking.

  1. 7×7×7=7□7 \times 7 \times 7 = 7^{\square}. The number in the box is
    Answer and solution

    Answer: (B) 33

    7 is multiplied by itself 3 times, so the power is 3.

    7×7×7=737 \times 7 \times 7 = 7^3

  2. In a3a^3, the power 3 shows that
    Answer and solution

    Answer: (D) aa is multiplied by itself 3 times

    a3=a×a×aa^3 = a \times a \times a: three aa's are multiplied.

  3. a×a×a×b×b×ba \times a \times a \times b \times b \times b in power form is
    Answer and solution

    Answer: (A) a3×b3a^3 \times b^3

    a×a×a=a3a \times a \times a = a^3 and b×b×b=b3b \times b \times b = b^3

    So it is a3×b3a^3 \times b^3.

  4. The next number in 1000,729,512,343,…1000, 729, 512, 343, \ldots is
    Answer and solution

    Answer: (C) 216216

    These are 10310^3, 939^3, 838^3, 737^3.

    Next is 63=2166^3 = 216

  5. 100 lies between
    Answer and solution

    Answer: (A) 434^3 and 535^3

    43=644^3 = 64 and 53=1255^3 = 125

    64<100<12564 < 100 < 125

  6. Which number is NOT the cube of any whole number?
    Answer and solution

    Answer: (D) 9090

    64=4364 = 4^3, 216=63216 = 6^3, 1000=1031000 = 10^3.

    90 is not in the table of cubes.

  7. □3=729\square^3 = 729. The number in the box is
    Answer and solution

    Answer: (A) 99

    9×9×9=7299 \times 9 \times 9 = 729

    So the box is 9.

  8. 143=14^3 =
    Answer and solution

    Answer: (B) 27442744

    14×14=19614 \times 14 = 196

    196×14=2744196 \times 14 = 2744

  9. A big cube is built from small cubes, with 20 small cubes along each edge. How many small cubes does it have?
    Answer and solution

    Answer: (B) 80008000

    Number = 20320^3

    20×20=40020 \times 20 = 400, 400×20=8000400 \times 20 = 8000

  10. 173=289×□17^3 = 289 \times \square. The number in the box is
    Answer and solution

    Answer: (D) 1717

    173=17×17×1717^3 = 17 \times 17 \times 17 and 17×17=28917 \times 17 = 289

    ∴173=289×17\therefore 17^3 = 289 \times 17

  11. Which number, multiplied by itself 3 times, gives −512-512?
    Answer and solution

    Answer: (C) −8-8

    (−8)3=−83=−512(-8)^3 = -8^3 = -512

  12. (−9)×(−9)×(−9)=(-9) \times (-9) \times (-9) =
    Answer and solution

    Answer: (B) −729-729

    (−9)×(−9)=81(-9) \times (-9) = 81

    81×(−9)=−72981 \times (-9) = -729

  13. (−40)3=(-40)^3 =
    Answer and solution

    Answer: (D) −64000-64000

    (−40)×(−40)=1600(-40) \times (-40) = 1600

    1600×(−40)=−640001600 \times (-40) = -64000

  14. 23+33+43=2^3 + 3^3 + 4^3 =
    Answer and solution

    Answer: (C) 9999

    23+33+43=8+27+642^3 + 3^3 + 4^3 = 8 + 27 + 64

    =99= 99

  15. 13+43=1^3 + 4^3 =
    Answer and solution

    Answer: (C) 6565

    13+43=1+641^3 + 4^3 = 1 + 64

    =65= 65

  16. Two big cubes are made of small cubes, with 2 and 5 small cubes along each edge. How many small cubes are there in the two cubes together?
    Answer and solution

    Answer: (A) 133133

    Total = 23+532^3 + 5^3

    23+53=8+1252^3 + 5^3 = 8 + 125

    =133= 133

  17. (−4)3+(−5)3=(-4)^3 + (-5)^3 =
    Answer and solution

    Answer: (B) −189-189

    (−4)3+(−5)3=−64+(−125)(-4)^3 + (-5)^3 = -64 + (-125)

    =−64−125= -64 - 125

    =−189= -189

  18. (−3)3+73=(-3)^3 + 7^3 =
    Answer and solution

    Answer: (C) 316316

    (−3)3+73=−27+343(-3)^3 + 7^3 = -27 + 343

    =316= 316

  19. (−3)3+13+(−2)3=(-3)^3 + 1^3 + (-2)^3 =
    Answer and solution

    Answer: (A) −34-34

    (−3)3+13+(−2)3=−27+1+(−8)(-3)^3 + 1^3 + (-2)^3 = -27 + 1 + (-8)

    =−27+1−8= -27 + 1 - 8

    =−34= -34

  20. One big cube has 8 small cubes along each edge and another has 3. How many more small cubes does the first one have?
    Answer and solution

    Answer: (C) 485485

    More = 83−338^3 - 3^3

    83−33=512−278^3 - 3^3 = 512 - 27

    =485= 485

  21. Ravi says 43−63=1524^3 - 6^3 = 152. The correct value is
    Answer and solution

    Answer: (D) −152-152

    43−63=64−2164^3 - 6^3 = 64 - 216

    =−152= -152

    Ravi took the smaller cube from the bigger one.

  22. 113−123=11^3 - 12^3 =
    Answer and solution

    Answer: (B) −397-397

    123=144×12=172812^3 = 144 \times 12 = 1728

    113−123=1331−172811^3 - 12^3 = 1331 - 1728

    =−397= -397

  23. −113−(−11)3=-11^3 - (-11)^3 =
    Answer and solution

    Answer: (C) 00

    (−11)3=−113(-11)^3 = -11^3

    −113−(−113)=−113+113=0-11^3 - (-11^3) = -11^3 + 11^3 = 0

  24. a3−(−a)3=a^3 - (-a)^3 =
    Answer and solution

    Answer: (D) 2a32a^3

    (−a)3=−a3(-a)^3 = -a^3

    a3−(−a3)=a3+a3=2a3a^3 - (-a^3) = a^3 + a^3 = 2a^3

  25. If x=−2x = -2 and y=−3y = -3, then x3+y3=x^3 + y^3 =
    Answer and solution

    Answer: (A) −35-35

    (−2)3+(−3)3=−8+(−27)(-2)^3 + (-3)^3 = -8 + (-27)

    =−8−27= -8 - 27

    =−35= -35