Multiply and divide by 1 and multiply by 0 | Year 4 Mathematics PDF Download

Understanding Multiplying by 1

• When you multiply by 1, the answer remains the same.
• For example:
  1 × 21 = 21 or 21 × 1 = 21
  You can think of it as 21 lots of 1 or 1 lot of 21. Both equal 21.
  1 × a number = that number or a number × 1 = that number.
  This applies to any number, whether big, small, or negative!
• For example:
  1 × 20,000 = 20,000
  1 × 2 = 2
  1 × -2 = -2
  A common mistake is to think that 1 × 1 = 2.
  1 plus 1 is 2, but 1 times 1 is 1.
  1 × 1 = 1

Dividing by 1

• When you divide by 1, the answer remains the same!
• For example:
  21 ÷ 1 = 21
  Imagine dividing 21 into groups of 1. You would have 21 groups.
  Or think of sharing 21 carrots with 1 bear. The bear would get all 21 carrots.
  That applies to any number, whether big, small, or negative!
• For example:
  20,000 ÷ 1 = 20,000
  21 ÷ 1 = 21
  -2 ÷ 1 = -2

Example: What do you think 1 ÷ 1 will be?
Sol: When you divide a number by 1, the result is the number you started with.
1 ÷ 1 = 1

Multiplying by 0

Multiplying by 0 always results in 0. Whether you do 0 × or × 0, the answer will be 0. For example:
21 × 0 = 0
Think of it as 21 groups of 0 or 21 groups of nothing. You could also think of it as adding 0 twenty-one times. This is why the result is always 0.
0 × a number = 0 or a number × 0 = 0
This makes the 0 times table very simple!