- Least Common Multiple
The smallest among the common multiples of two numbers is called their least common
multiple.
To find the L.C.M
Step 1. Write the multiples of the first number
- Write the multiples of the second number
- Write the common multiples
- Write the least common multiple
Eg. : L.C.M of 3 and 5 is 15 since 15 is the common multiple, least in magnitude for
both. The pre-requisite for knowing the concept of L.C.M. is the mastery of the
multiplication tables.Beads can be used to teach this concept. Considering the above said example, arrange
different heaps of beads in multiples of 3 and 5. It is clear that, of the multiples of 3
which are 6, 9, 12, 15, 18, etc, and 5, 10, 15, 20 etc, 15 is the least in magnitude and
hence it is the least common multiple of 3 and 5.- Factor
A factor is a number or quantity that when divided with another produces the given
number or expression without any remainder.
For example, consider the number 12. Note that number 12 is divisible by 1, 2, 3, 4,
6 and 12. Hence the divisors are 1, 2, 3, 4, 6 and 12 and the factors are obtained by
excluding the number 1 and 12. Therefore the factors of 12 are 2, 3, 4 and 6.To teach the concept provide the child with 12 beads. Ask the child to regroup the
12 beads, say, in 1’s, 2’s, 3’s etc., so that each group contains equal number of beads.
The number of beads in each grouping becomes a divisor of 12. Once the child has
obtained all the divisors, then the idea of factors may be explained orally, that is by
saying that if 1 and the given number are excluded then the remaining numbers are
the factors.