0
1+2=3
3+4=7
7x3=21
(1+2)x(3+4)
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When you subtract 1 square number from another the answer is 21 what are the 2 squared numbers?
They are: 25-4 = 21
Is 21 and 27 prime and composite numbers?
A prime number has exactly two factors, 1 and the number itself. The factors of 21 are 1, 3, 7, and 21, and the factors of 27 are 1, 3, 9, and 27. Since 21 and 27 have more than 2 factors, they are composite numbers.
Are these numbers prime or composite 21?
21 is a composite number. A prime number has only 2 factors which are 1 and itself. Composite numbers are everything else except 1 and 0. 1 and 0 are neither prime, nor composite.
Are prime numbers same as odd numbers?
No.Prime numbers are numbers that can only be divided evenly by itself and 1.For example, the number 7 can only be divided by 7 and 1.Odd numbers are numbers that end in (or are) 1, 3, 5, 7, or 9.For example, the number 21 is odd since it ends in a 1, but it is not prime because itcan be divided by 1, 21, 7, and 3. (7 times 3 = 21.)2 is a prime number and is even not odd - it is the only even prime number.
What is the sixth triangular number?
Triangular numbers are numbers that are formed from the sum 1+2+3+4... The equation for the nth triangle number is (n2+n)/2 In this case, we want the sixth triangle number, so feed this into the equation: (62+6)/2 =(36+6)/2 =42/2 =21 Thus the sixth triangle number is 21.
What number is the next logical number in the following sequence of numbers 1 1 2 3 5 8 13?
21. This is the Fibonacci series.
What prime numbers 21?
A prime number has only 2 factors which are 1 and itself. Composite numbers are everything else except 1 and 0. 1 and 0 are neither prime, nor composite. 21 is composite.
What number is the next logical number in the sequence of numbers 1 1 2 3 5 8 13 21?
34. Each number is the sum of the two preceding numbers. This is called the Fibonacci Sequence.
The sum of two numbers is 21 The difference of the two numbers is 19 What are the two numbers?
20 and 1 Seems to be a common problem. Add the sum to the difference and divide by 2 gives one number. Then start over and subtract the smaller of the two givens from the larger and then divide by 2 to get the other number. So here you have (21+19)/2 and (21-19)/2
What is the next number in this logical sequence 1 1 2 3 5 8 13?
21. Add the last 2 numbers to get the next.
What are adjacent number in a clock whose sum is triangle number?
{1, 2}, {7, 8} and {10, 11}. The triangular numbers are 1, 3, 6, 10, 15, 21, 28, ... The sum of two adjacent numbers is odd, so adjacent numbers that sum to 1, 3, 15, 21 are the solution. 1 is impossible, leaving 3, 15 & 21 as possible sums, giving the adjacent numbers {1, 2}, {7, 8} & {10, 11}
Is 21 a number in the Fibonacci sequence?
Yes, 21 is a number in the Fibonacci sequence. Numbers are usually found by adding up 2 numbers.
