In which of the following multiplications is the product less than 1? Can you find the answer without actually doing the multiplications? (a) (b) (c) (d)
The product is less than 1 in cases (b) and (d).
Rule: When both numbers being multiplied are between 0 and 1, the product is less than both numbers and therefore less than 1. When one number is greater than 1 and one is between 0 and 1, the product is between the two numbers.
(a) : One number is greater than 1 and one is between 0 and 1 Product is greater than the smaller number but could be greater than 1 ∴ Product greater than 1
(b) : Both 0.7 and 0.6 are between 0 and 1 Product is less than both numbers and definitely less than 1 ∴ Product less than 1
(c) : One number is greater than 1 and one is between 0 and 1 Product is greater than the smaller number but could be greater than 1 ∴ Product greater than 1
(d) : Both 0.07 and 0.06 are between 0 and 1 Product is less than 1 ∴ Product less than 1
Explanation
As explained in the chapter, when both numbers being multiplied are between 0 and 1, the product is less than both numbers and therefore less than 1. When one number is greater than 1 and one is between 0 and 1, the product is between the two numbers.
Solution Steps
Apply the rule: when both numbers being multiplied are between 0 and 1, the product is less than both numbers and therefore less than 1.
When one number is greater than 1 and one is between 0 and 1, the product is between the two numbers.
For (a) : one number (7) is greater than 1, one (0.6) is between 0 and 1, so product is greater than 1.
For (b) : both numbers are between 0 and 1, so product is less than 1.
For (c) : one number (6) is greater than 1, one (0.7) is between 0 and 1, so product is greater than 1.
For (d) : both numbers are between 0 and 1, so product is less than 1.
Conclusion: Products less than 1 are in cases (b) and (d).