1.3 Lowest common multiples · Unit 1 Integers

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2 · Key words

multipleThe result of multiplying a number by a whole number; the multiples of 4 are 4, 8, 12, 16, …

common multipleA number that is a multiple of two or more numbers.

lowest common multiple (LCM)The smallest number that is a multiple of two or more numbers.

digitOne of the symbols 0–9 used to write a number.

3 · Summary of the sectionrevise from this

The multiples of a number are its times table: multiples of 4 are 4, 8, 12, 16, 20, …
A common multiple of two numbers appears in both times tables.
The lowest common multiple (LCM) is the smallest of those common multiples.
Method: list the multiples of the larger number and stop at the first one that the smaller number divides into.
If two numbers share no factors, LCM = a × b, e.g. LCM(5, 8) = 40.
If one number is a multiple of the other, the LCM is the larger number, e.g. LCM(4, 12) = 12.

PDFPrintable worksheet All 56 questions, space to work PDFWorked answers Full solutions, not just the answer

Video lessons3 videos

Multiples | Common Multiples | Least Common Multiple (LCM)

American Math with Mr. J

Builds from multiples to common multiples to the LCM — the best video to watch first.

Least Common Multiple (LCM)

American Math with Mr. J

Focused practice finding the LCM of a pair by listing multiples, the Stage 7 method.

LCM and Common Multiples

British Corbettmaths

Uses the term “lowest common multiple”, which is the wording the Cambridge Stage 7 framework uses.

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Lowest common multiples