Numeracy

Multiplication Basics





What is Multiplication?

  • Multiplication is adding a number to itself repeatedly.
    Example: ( 4 * 3 = 4 + 4 + 4 = 12 ).
  • Common Symbols:
  • ‘×’ for written math.
  • ‘*’ in spreadsheets or coding.

Key Rules of Multiplication

  1. Any number × 0 = 0: ( 200 * 0 = 0 ).
  2. Any number × 1 = Same number: ( 200 * 1 = 200 ).
  3. Doubling (×2): Multiply by 2 to double the number.
  4. Multiplying by 10, 100, etc.:
  5. Add the same number of zeros as in the multiplier.
  6. ( 4 * 2000 = 4 * 2 = 8 ), then add 3 zeros: 8000.

Multiplication Table

The times table (1–10) helps find answers quickly. Example:
- To find ( 4 * 6 ), locate 4 in the top row and 6 in the left column. The intersection is 24.
- Order doesn't matter: ( 4 * 6 = 6 * 4 ).


Real-World Example:

  • Cinema Tickets:
  • 4 tickets at $8 each: ( 4 * 8 = 32 ).
  • Total cost: $32.

Steps for Multiplying Larger Numbers:

Example: ( 23 * 14 )

  1. Set up columns (hundreds, tens, units).
  2. Multiply each digit in the bottom number with the digits in the top number, starting from the right.
  3. Add intermediate results:
  4. ( 4 * 3 = 12 ) Write 2 in units, carry over 1 to tens.
  5. ( 4 * 20 = 80 ).
  6. ( 10 * 3 = 30 ).
  7. ( 10 * 20 = 200 ).
  8. Add ( 12 + 80 + 30 + 200 = 322 ).

Multiplying More Than Two Numbers:

  1. Multiply the first two numbers.
  2. Multiply the result by the next number.
    Example: ( 7 * 5 * 4 ).
  3. Step 1: ( 7 * 5 = 35 ).
  4. Step 2: ( 35 * 4 = 140 ).

Negative Numbers in Multiplication

  1. Positive × Negative = Negative:
  2. ( 15 * (-4) = -60 ).
  3. Negative × Negative = Positive:
  4. ( (-15) * (-4) = 60 ).

Quick Calculation Tips:

  1. Break down large numbers:
  2. ( 12 * 140 = (10 * 140) + (2 * 140) = 1400 + 280 = 1680 ).
  3. Use patterns: Memorize tables and repeat similar calculations for speed.

Master these steps, and multiplication becomes straightforward!


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