Question

How many different products can be obtained by multiplying two or more of the numbers 3, 5, 7, 11 (without repetition)?

Answer 1

We need to find the no. of ways of obtaining a product by multiplying two or more from the numbers 3, 5, 7, 11.

The number of ways = (no. of ways of multiplying two numbers) + (no. of ways of multiplying three numbers) + (no. of multiplying four numbers)

= ⁴C₂ + ⁴C₃ + ⁴C₄

On using the formula,

ⁿC_r = n!/r!(n – r)!

= 12/2 + 4 + 1

= 6 + 4 + 1

= 11

Thus, the total number of ways of product is 11 ways.