Whole Numbers · 5 sample questions from the school syllabus. Try each one, then open the answer and the worked solution.
1. Which of the following is a whole number but NOT a natural number?
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Answer: A) 0
Whole numbers are 0, 1, 2, 3, …. Natural numbers start at 1. So 0 is the only whole number that is not a natural number. (-1 and 0.5 are not whole numbers at all.)
2. Riya bought 6 books at 99 rupees each. Using the distributive property, what was the total cost in rupees?
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Answer: C) 594
6 × 99 = 6 × (100 - 1) = 600 - 6 = 594. The total cost is 594 rupees.
3. Find 1,005 - 998 using mental maths.
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Answer: D) 7
Count up from 998 to 1,005: 998 + 7 = 1,005. So the difference is 7.
4. Meera tests each operation on many pairs of whole numbers. Which PAIR of operations always gives a whole-number answer?
- AAddition and subtraction
- BAddition and multiplication
- CMultiplication and division
- DSubtraction and division
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Answer: B) Addition and multiplication
Adding or multiplying any two whole numbers always lands back inside the whole numbers, so these two are closed. Subtraction fails, since 3 - 8 = -5, and division fails, since 8 ÷ 5 = 1.6. Any pair containing subtraction or division is therefore wrong.
5. A school in Ranchi must seat 1,000 students in buses that hold 45 students each. Since part of a bus cannot be used, how many buses are needed so that every student gets a seat?
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Answer: C) 23
45 × 22 = 990, so 22 buses seat 990 students and 10 are still left standing. Those 10 need one more bus, giving 23 buses. Answering 22 ignores the remainder, and 22.2 shows why division is not closed on whole numbers: the exact quotient is not a whole number, and here the situation forces us to round UP.