lesson
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Imagine you have 4 boxes with 15 toy cars in each box. Counting all 60 cars in your head sounds tricky!
What if you could turn that tricky problem into an easy one using a math secret?
The Double and Half Trick
When you multiply two numbers, you can cut one number in half and make the other number double (twice as big). The total number of items stays exactly the same!
📊Interactive diagram
Why does moving the pieces around never change our total?
Why It Works
Think of a chocolate bar with 4 rows of 5 squares. That makes 20 sweet pieces in all.
If you snap the bar in half and line the two long pieces up end-to-end, you now have 2 rows of 10 squares. You did not add or eat any chocolate, so you still have 20 pieces!
📊Interactive diagram
The Doubling and Halving strategy relies on the constant product principle, which is based on the associative property of multiplication.
Multiplying one factor by 2 and dividing the other factor by 2 leaves the product unchanged, as (a×2)×(b÷2)=a×b×(2×21)=a×b×1.
Mathematically, The Doubling and halving strategy relies on the constant product principle, which is based on the associative property of multiplication.