Mathematics
Why does a negative times a negative equal a positive? Think of it in terms of action and debt. If a negative number represents a debt, then multiplying by a negative number represents the removal of that debt. (Hint: If someone takes away (–) four of your debts that are each worth ₹3 (that is, –3), you are effectively ₹12 richer! Therefore, (–3) × (–4) = +12.)
Answer
A negative number represents a debt (an amount owed) and a negative multiplier represents the removal (taking away) of those debts.
Consider the following situation :
Suppose I have 4 debts, each worth ₹3.
Each debt is represented as -3.
If someone takes away (removes) these 4 debts, I am no longer in debt and my wealth effectively increases by ₹12.
Mathematically :
⇒ (-3) × (-4)
⇒ +12.
So, removing 4 debts of ₹3 each makes me ₹12 richer.
Hence, multiplying a negative number by a negative number gives a positive number, because removing debts increases wealth.
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