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Meera tests each operation on many pairs of whole numbers. Which PAIR of operations always gives a whole-number answer?

Class 6Whole NumbersWhole Numbers
  • AAddition and subtraction
  • BAddition and multiplication
  • CMultiplication and division
  • DSubtraction and division

Step-by-Step Solution

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.
Answer: B) Addition and multiplication

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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