15 is an odd number less than 20.
1st odd number . . . 1 (1 less than double 1)2nd odd number . . . 3 (1 less than double 2)3rd odd number . . . 5 (1 less than double 3)4th odd number . . . 7 (1 less than double 4)5th odd number . . . 9 (1 less than double 5)Are you seeing a pattern yet ?6th odd number . . . 11 (1 less than double 6)7th odd number . . . 13 (1 less than double 7)...Qth odd number . . . . (1 less than double Q)
4 x 5
The smallest odd number greater than 50 is 51.It doesn't matter what it's less than.
All multiples of 6 are even numbers.
Perfect squares have an odd number of factors. There are 31 perfect squares less than 1000.
10 is such a number.
65
45
-13 is an odd number which is less than 5.
9
The answer is 9. It is a multiple of 3. 3+3+3=9. It is less than 20: 20-9=11.It is not a prime number. It is odd, and it is not a factor of 30. 30/9=3.3333333333
1st odd number . . . 1 (1 less than double 1)2nd odd number . . . 3 (1 less than double 2)3rd odd number . . . 5 (1 less than double 3)4th odd number . . . 7 (1 less than double 4)5th odd number . . . 9 (1 less than double 5)Are you seeing a pattern yet ?6th odd number . . . 11 (1 less than double 6)7th odd number . . . 13 (1 less than double 7)...Qth odd number . . . . (1 less than double Q)
1st odd number . . . 1 (1 less than double 1)2nd odd number . . . 3 (1 less than double 2)3rd odd number . . . 5 (1 less than double 3)4th odd number . . . 7 (1 less than double 4)5th odd number . . . 9 (1 less than double 5)Are you seeing a pattern yet ?6th odd number . . . 11 (1 less than double 6)7th odd number . . . 13 (1 less than double 7)...Qth odd number . . . . (1 less than double Q)
3
4 x 5
Every prime number except 2 must be odd. This is because if it were even it would be divisible by 2 and so wouldn't be a prime number. The next point to note is that all odd numbers are one more or one less than a multiple of 4. Because 2 more than a multiple of 4 is even, and 3 more than a multiple of 4 is the same as 1 less than the multiple of 4 above. Thus every prime number except 2 must be 1 more or 1 less than a multiple of 4.
All Mersenne primes are one less than some multiple of two. Any multiple of two is even, so any multiple one less than a multiple of two must be odd.