Page 53 - Maths Skill - 6

Prime Time 51

MIND MAP

Prime Time

Numbers

Even Odd Prime Co-Prime Composite
Divisible Not Divisible having exactly having only one as having more
by 2 by 2 two factors 1 their common factor than two factors
and itself i.e. (3, 7)

Divisibility Test Twin Prime
Pair of prime members
DIVISOR RULES
2 If unit place digits are 0, 2, 4, 6, 8 differ by 2
3 Sum of digits is divisible by 3 i.e. (3, 5) (5, 7)
4 Last two digits of number is divisible by 4
5 If ones place is either 0 or 5
6 If number is divisible by 2 and 3 both
8 Last three digits of number is divisible by 8 For any two numbers a and b
9 Sum of digits is divisible by 9 HCF × LCM = a × b
10 If unit place of number is 0
11 Difference of sum of digits at even places
and odd places is either 0 or multiple of 11

Multiples
Factors � A multiple is always greater

� A factor is always smaller than or equal than or equal to its number.
to its number. � Every number is a multiple of
� A factor of a number is an exactly itself.
divisor of that number. � Multiples of any number can

� 1 is the factor of every number. be infinite.