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LESSON 2: C. MULTIPLICATION
4. Multiplicative Identity Property: The product of any number and one is the original
number. (Multiplying 1 to a number does NOT change the number.)
For example: 5 × 1 = 5 ∎
Thus, one (0) is called the Identity Number for multiplication.
5. The Zero Product Property: A product of factors is zero if and only if one or more
of the factors is zero.
For example: 8 × 0 = 0 ∎
6. Multiplication by 0.1, 0.01, 0.001, etc.
When we multiply numbers by 0.1, 0.01, 0.001, etc., we simply move the
decimal point in the multiplicand to the left as many places as the number of
decimal places in the multiplier.
Example 1. 747 × 0.1 = 74.7
Example 2. 747 × 0.01 = 7.47
Example 3. 747 × 0.001 = 0.747
` 7. Multiplication by 10, 100, and 1,000
When we multiply numbers by 10, 100, 1,000, and so on, we simply
attach as many zeroes to the multiplicand as there are zeroes in the multiplier. This
shortcut can greatly speed up our multiplication process.
Example 1. ₱ 747 × 10 = ₱ 7,470
₱ 7.47 × 10 = ₱ 74.70
Example 2. ₱ 747 × 100 = ₱ 74,700
₱ 7.47 × 100 = ₱ 747.00
Example 3. ₱ 747 × 1,000 = ₱ 747,000
₱ 7.47 × 1,000 = ₱ 7,470.00
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