Call the two digit number xy. So: 10x + y = 2(x + y)
Multiplying out: 10x + y = 2x +2y
Rearranging: 8x = y We can at this point introduce the constraints that x and y must be integers between 0 and 9. Only one value of x will allow this: 1. So y = 8. The answer, then, is 18. Call the two digit number xy. So: 10x + y = 2(x + y)
Multiplying out: 10x + y = 2x +2y
Rearranging: 8x = y We can at this point introduce the constraints that x and y must be integers between 0 and 9. Only one value of x will allow this: 1. So y = 8. The answer, then, is 18.
18 is the only number that matches these criteria.
56
The difference between a number x and twice y is equal to fifteen.
21
The Answer is 36 btw. 3 + 6 = 9 3 x 6 = 2(3x6) 2(18) = 36
8 is the same as the sum of the digits of its cube, 512.
18 1 + 8 = 9 and 9 x 2 = 18
18
81
18 is the only number that matches these criteria.
18. 1+8=9 9x2=18
Yes, unless you include 0.
Any number whose sum of its digits are equal to a multiple of 3, is divisible by 3. In this instance, the sum of the digits of the number 34215 is equal to 15, which is divisible by 3, and therefore the number is divisible by 3.
26
36
18 is the only number (other than 0) that is twice the sum of its digits.
composite number