Exercise · ZW-CYCLIC-GROUP-004 · ★☆☆ Basic
How many subgroups does \((\mathbb{Z}_{18},+)\) have?
Choose one option.
Show answer
- A. 6
Explanation
A cyclic group of order \(n\) has exactly one subgroup for each divisor of \(n\). The divisors of 18 are \(1,2,3,6,9,18\): six subgroups.
Review the concept: Cyclic group
A cyclic group is a group \(G\) with an element \(g\), called a generator, such that every element of \(G\) is a power of \(g\).
\[G=\langle g\rangle=\{\,g^k : k\in\mathbb{Z}\,\}\]
More practice problems: cyclic group
- ZW-CYCLIC-GROUP-001 How many generators does the cyclic group (ℤ_12,+) have?
- ZW-CYCLIC-GROUP-002 Which of the following elements generates (ℤ_10,+)?
- ZW-CYCLIC-GROUP-003 Which of the following groups is NOT cyclic?
- ZW-CYCLIC-GROUP-005 Which of the following elements generates the group (ℤ_7^*,·)?
- ZW-CYCLIC-GROUP-006 How many elements does the subgroup of (ℤ_24,+) generated by 9 and 15 have?
- ZW-CYCLIC-GROUP-007 Which of the following statements is true?
- ZW-CYCLIC-GROUP-008 How many elements of order 4 does (ℤ_20,+) have?
- ZW-CYCLIC-GROUP-009 Let G=langle grangle be an infinite cyclic group. How many generators does G have?