Find the number of different ways in which 711 can be expressed as the product…

2025

Find the number of different ways in which 711 can be expressed as the product of three factors.

  1. A.

    12

  2. B.

    10

  3. C.

    16

  4. D.

    14

Show answer & explanation

Correct answer: C

Concept: To express a prime power pn as a product of three positive factors, where the order of the factors does not matter, split the exponent n among the three factors as px . py . pz with x + y + z = n and x, y, z >= 0 (a factor of 1 corresponds to an exponent of 0). The number of such unordered triples (x, y, z) equals the number of partitions of n into at most three parts.

Application: Here the number is 711, so n = 11. Count every partition of 11 into at most three parts, grouped by how many parts are used:

  1. One part: {11} -- 1 way (the three factors are 711, 1, 1).

  2. Two parts: (10, 1), (9, 2), (8, 3), (7, 4), (6, 5) -- 5 ways.

  3. Three parts: (9, 1, 1), (8, 2, 1), (7, 3, 1), (7, 2, 2), (6, 4, 1), (6, 3, 2), (5, 5, 1), (5, 4, 2), (5, 3, 3), (4, 4, 3) -- 10 ways.

  4. Adding the three cases: 1 + 5 + 10 = 16.

Cross-check: The number of partitions of n into at most three parts is also given by the nearest-integer formula round((n + 3)2 / 12). For n = 11 this gives round(142 / 12) = round(196 / 12) = round(16.33) = 16, matching the direct count above.

So 711 can be expressed as a product of three factors in 16 distinct ways.

Explore the full course: Deloitte Nla