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Question :- What is a Prime Number?

Answer:- These are whole numbers that are only divisible by 1 and by the number itself.

e.g. 11 = Divisible by 1 & 11

e.g. 31 = Divisible by 1 & 31

Non-prime numbers can be divided by two or more numbers.

e.g. 9 = Divisible by 1, 3 & 9

Prime Factors

This is prime numbers that are multiplied together give arrive at the number being considered.

e.g. The prime factors of 171 are 3, 3, 19

So 171 = 3 x 3 x 19

To find the Prime Factors of an odd number like 171

1) Look up the prime factor in the table below for 171 which is 3.

2) Divide 171 by 3 to give 57.

3) Look up 57 in the table below the smallest factor is 3 again.

4) Divide 57 by 3 to give 19.

5) Look up 19 in the table below the smallest factor is a P which means its a prime number itself.

To find the Prime Factors of an even number like 60

1) The smallest prime factor for an even is 2.

2) Divide 60 by 2 to give 30.

3) Divide 30 by 2 to give 15.

4) Look up 15 in the table below the smallest factor is 3 again.

5) Divide 15 by 3 to give 3.

6) Look up 3 in the table below the smallest factor is a P which means its a prime number itself.

Odd Prime Numbers & smallest factor lookup table

000s100s200s300s400s500s600s700s800s900s
1PP37P3PP317
3PP7313P319113
5P355355355
7PP3P113P73P
11P3PP37133PP
13PP3P73P23311
153553553553
17P37P311P3197
19P7311P3PP3P
21311133PP37P3
23P3P173P73P13
255535535535
273PP37173PP3
29P3P7323173PP
31PP3PP3P1737
3337P3P133P73
355355355355
37PP3P1937113P
393PP3P73PP3
41P3P113PP329P
43P1137P3PP323
453553553553
47P313P3PP37P
497P3PP3117313
513PP311193P233
53P311P37P3PP
555535535535
573PP3PP3PP3
59P37P313P3P7
61P7319P3PP331
633PP3PP37P3
655355355355
67PP3PP323133P
69313P37P3P113
71P3P73P11313P
73PP3P113PP37
753553553553
7773P133PP3PP
79PP3PP3719311
813PP3137311P3
83P3PP311P3PP
855535535535
87P31173PP3PP
89P317P319133723
917P317P3P73P
933PP317P313193
955355355355
97PP3P7317P3P
993P133PP317293