Solved Questions on Number Sense
1. Rock bought twelve melons for $4 each. What is the total amount Rock has to pay in Roman numerals?
a) LXVIII
b) LVXIII
c) XLVIII
d) XVLIII
Answer: c) XLVIII
Explanation: Cost of 1 melon = $4
Cost of 12 melons = $4 × 12 = $48
Therefore, Rock has to pay XLVIII.
2. Fill the blank: CXVIII + CDXXIII = _________
a) DLXI
b) DXLI
c) DXIL
d) DXIX
Answer: b) DXLI
Explanation: The conversion of Roman numerals into numbers is:
CXVIII = C + X + VIII = 100 + 10 + 8 = 118
CDXXIII = (D − C) + X + X + VIII
= (500 − 100) + 10 + 10 + 3
= 400 + 10 + 10 + 3
= 423
Hence,
CXVIII + CDXXIII = 118 + 423
= 541
= 500 + 40 + 1
= D + XL + I
=DXLI
3. What is the predecessor of a hundred million?
a) Ninety-nine million nine hundred ninety-nine thousand nine hundred and nine
b) Ninety-nine million nine hundred ninety thousand nine hundred and ninety-nine
c) Ninety-nine million nine thousand ninety-nine thousand nine hundred and ninety-nine
d) Ninety-nine million nine hundred ninety-nine thousand nine hundred and ninety-nine
Answer: d) Ninety-nine million nine hundred ninety-nine thousand nine hundred and ninety-nine
Explanation: Hundred million = 100,000,000
Predecessor of ten million = 100,000,000 − 1 = 99,999,999
The number 99,999,999 in words is “Ninety-nine million nine hundred ninety-nine thousand nine hundred and ninety-nine”.
4. Two bundles of rope are 26 m and 39 m long. The rope is to be cut into pieces of equal length. Find the maximum length of each piece.
a) 11 m
b) 13 m
c) 21 m
d) 23 m
Answer: b) 13 m
Explanation: The maximum length of each individual piece can be found by using H.C.F. of 26 and 39.
HCF of 26 and 39 = 13
Maximum length of each piece = HCF of 26 and 39 = 13 metres
5. Granny had 45 red roses, 15 white roses, 35 yellow roses and 25 black roses. She wants to make baskets of roses with the same number of each colour roses in each basket. What is the greatest number of baskets that she can make?
a) 5
b) 15
c) 30
d) 45
Answer: a) 5
Explanation: Granny had 45 red roses, 15 white roses, 35 yellow roses and 25 black roses. She needs to find the greatest number which exactly divides 45, 15, 35 and 5.
This means she should find HCF of 15, 25, 35 and 45.
Using the prime factorisation method:
Hence, the greatest number of baskets is 5 that she can make.
