What is the least positive integer that is not a factor of 2
3个回答

positive integers from smallest:

1,2,3,4,...

1 is a factor,25!=1*25!

2 is a prime number

3 is a prime number

4 is a factor,25!=4*1*2*3*5*6*...*25

25!指的是25阶乘=25*24*...*1

5显然是factor

6,7,8,9,10,...,25显然都是factor

26=2*13也是

27=3*3*3,25!中有3和9,所以也是factor

28=4*7,factor

29是prime

30=3*10

31prime

32=4*8,factor

33=3*11,factor

34=2*17,factor

35=5*7,factor

36=4*9,factor

37prime

38=2*19,factor

39prime

40=4*10,factor

41prime

42=2*21factor

43prime

44=4*11factor

45=5*9factor

46=2*23factor

47prime

48=6*8factor

49=7*7,25!包含7和14,factor

50=5*10factor

51=3*17factor

52=4*13factor

53prime

54=2*3*9,factor

55=5*11,factor

56=7*8,factor

57=3*19,factor

58=2*29,not a factor and not a prime

So 58 is the least positive integer that is not a factor of 25!and is not a prime number.