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Rahul works out 40 - 65 and Sneha works out . Whose answer is a whole number?

Class 6Whole NumbersWhole Numbers
  • AOnly Sneha's
  • BOnly Rahul's
  • CBoth of their answers
  • DNeither of their answers

Step-by-Step Solution

, a whole number, because multiplication is closed on whole numbers. But 40 - 65 = -25, a negative integer, so Rahul lands outside the whole numbers. The common mistake is to assume the order in a subtraction can be swapped and quietly compute 65 - 40 = 25 instead.
Answer: A) Only Sneha's

Key idea: Closure: when an operation 'stays inside' the whole numbers

Adding two whole numbers always gives a whole number — addition is **closed** on whole numbers. Multiplying two whole numbers always gives a whole number — multiplication is **closed** too. But subtraction is **not** closed: 5 − 7 = −2, which is not a whole number. Division is also not closed: 7 ÷ 2 = 3.5, not a whole number. Closure is the property that lets us trust an operation never to take us 'outside' the world of whole numbers.

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