{ localUrl: '../page/least_common_multiple.html', arbitalUrl: 'https://arbital.com/p/least_common_multiple', rawJsonUrl: '../raw/65x.json', likeableId: '3536', likeableType: 'page', myLikeValue: '0', likeCount: '2', dislikeCount: '0', likeScore: '2', individualLikes: [ 'JaimeSevillaMolina', 'JohannesSchmitt' ], pageId: 'least_common_multiple', edit: '4', editSummary: '', prevEdit: '3', currentEdit: '4', wasPublished: 'true', type: 'wiki', title: 'Least common multiple', clickbait: '', textLength: '2002', alias: 'least_common_multiple', externalUrl: '', sortChildrenBy: 'likes', hasVote: 'false', voteType: '', votesAnonymous: 'false', editCreatorId: 'KevinClancy', editCreatedAt: '2016-09-25 21:50:36', pageCreatorId: 'JohannesSchmitt', pageCreatedAt: '2016-09-24 09:10:09', seeDomainId: '0', editDomainId: 'AlexeiAndreev', submitToDomainId: '0', isAutosave: 'false', isSnapshot: 'false', isLiveEdit: 'true', isMinorEdit: 'false', indirectTeacher: 'false', todoCount: '0', isEditorComment: 'false', isApprovedComment: 'true', isResolved: 'false', snapshotText: '', anchorContext: '', anchorText: '', anchorOffset: '0', mergedInto: '', isDeleted: 'false', viewCount: '38', text: '[summary: The **least common multiple (LCM)** of two positive [45h natural numbers] a, b is the smallest natural number that both a and b divide, so for instance LCM(12,10) = 60.]\n\nGiven two positive natural numbers $a$ and $b$, their **least common multiple** $\\text{LCM}(a,b)$ is the smallest natural number divided by both $a$ and $b$. As an example take $a=12, b=10$, then the smallest number divided by both of them is $60$.\n\nThere is an equivalent definition of the LCM, which is strange at first glance but turns out to be mathematically much more suited to generalisation: the LCM $l$ of $a$ and $b$ is the natural number such that for every number $c$ divisible by both $a$ and $b$, we have $l$ divides $c$.\nThis describes the LCM as a [3rc poset least upper bound] (namely the [-3rb] $\\mathbb{N}$ under the relation of divisibility).\n\nNote that for $a$, $b$ given, their product $ab$ is a natural number divided by both of them. The least common multiple $\\text{LCM}(a,b)$ divides the product $ab$ and for $\\text{GCD}(a,b)$ the [-5mw] of $a, b$ we have the formula\n$$a\\cdot b = \\text{GCD}(a,b) \\cdot \\text{LCM}(a,b). $$\nThis formula offers a fast way to compute the least common multiple: one can compute $\\text{GCD}(a,b)$ using the [euclidean_algorithm] and then divide the product $ab$ by this number.\n\nIn practice, for small numbers $a,b$ it is often easier to use their factorization into [4mf prime numbers]. In the example above we have $12=2 \\cdot 2 \\cdot 3$ and $10=2 \\cdot 5$, so if we want to build the smallest number $c$ divided by both of them, we can take $60=2 \\cdot 2 \\cdot 3 \\cdot 5$. Indeed, to compute $c$ look at each prime number $p$ dividing one of $a,b$ (in the example $p=2,3,5$). Then writing $c$ as a product we take the factor $p$ the maximal number of times it appears in $a$ and $b$. The factor $p=2$ appears twice in $12$ and once in $10$, so we take it two times. The factor $3$ appears once in $12$ and zero times in $10$, so we only take it once, and so on.', metaText: '', isTextLoaded: 'true', isSubscribedToDiscussion: 'false', isSubscribedToUser: 'false', isSubscribedAsMaintainer: 'false', discussionSubscriberCount: '2', maintainerCount: '2', userSubscriberCount: '0', lastVisit: '', hasDraft: 'false', votes: [], voteSummary: 'null', muVoteSummary: '0', voteScaling: '0', currentUserVote: '-2', voteCount: '0', lockedVoteType: '', maxEditEver: '0', redLinkCount: '0', lockedBy: '', lockedUntil: '', nextPageId: '', prevPageId: '', usedAsMastery: 'false', proposalEditNum: '0', permissions: { edit: { has: 'false', reason: 'You don't have domain permission to edit this page' }, proposeEdit: { has: 'true', reason: '' }, delete: { has: 'false', reason: 'You don't have domain permission to delete this page' }, comment: { has: 'false', reason: 'You can't comment in this domain because you are not a member' }, proposeComment: { has: 'true', reason: '' } }, summaries: {}, creatorIds: [ 'PatrickStevens', 'JohannesSchmitt', 'KevinClancy' ], childIds: [], parentIds: [ 'math' ], commentIds: [], questionIds: [], tagIds: [], relatedIds: [], markIds: [], explanations: [], learnMore: [], requirements: [], subjects: [], lenses: [], lensParentId: '', pathPages: [], learnMoreTaughtMap: {}, learnMoreCoveredMap: {}, learnMoreRequiredMap: {}, editHistory: {}, domainSubmissions: {}, answers: [], answerCount: '0', commentCount: '0', newCommentCount: '0', linkedMarkCount: '0', changeLogs: [ { likeableId: '3549', likeableType: 'changeLog', myLikeValue: '0', likeCount: '1', dislikeCount: '0', likeScore: '1', individualLikes: [], id: '19728', pageId: 'least_common_multiple', userId: 'KevinClancy', edit: '4', type: 'newEdit', createdAt: '2016-09-25 21:50:36', auxPageId: '', oldSettingsValue: '', newSettingsValue: '' }, { likeableId: '0', likeableType: 'changeLog', myLikeValue: '0', likeCount: '0', dislikeCount: '0', likeScore: '0', individualLikes: [], id: '19710', pageId: 'least_common_multiple', userId: 'PatrickStevens', edit: '3', type: 'newEdit', createdAt: '2016-09-24 10:30:21', auxPageId: '', oldSettingsValue: '', newSettingsValue: '' }, { likeableId: '0', likeableType: 'changeLog', myLikeValue: '0', likeCount: '0', dislikeCount: '0', likeScore: '0', individualLikes: [], id: '19709', pageId: 'least_common_multiple', userId: 'PatrickStevens', edit: '2', type: 'newEdit', createdAt: '2016-09-24 10:29:49', auxPageId: '', oldSettingsValue: '', newSettingsValue: '' }, { likeableId: '0', likeableType: 'changeLog', myLikeValue: '0', likeCount: '0', dislikeCount: '0', likeScore: '0', individualLikes: [], id: '19708', pageId: 'least_common_multiple', userId: 'PatrickStevens', edit: '0', type: 'newParent', createdAt: '2016-09-24 10:26:36', auxPageId: 'math', oldSettingsValue: '', newSettingsValue: '' }, { likeableId: '3540', likeableType: 'changeLog', myLikeValue: '0', likeCount: '1', dislikeCount: '0', likeScore: '1', individualLikes: [], id: '19706', pageId: 'least_common_multiple', userId: 'JohannesSchmitt', edit: '1', type: 'newEdit', createdAt: '2016-09-24 09:10:09', auxPageId: '', oldSettingsValue: '', newSettingsValue: '' } ], feedSubmissions: [], searchStrings: {}, hasChildren: 'false', hasParents: 'true', redAliases: {}, improvementTagIds: [], nonMetaTagIds: [], todos: [], slowDownMap: 'null', speedUpMap: 'null', arcPageIds: 'null', contentRequests: {} }