Question
Solve the mathematical puzzle.
Determine the digits of R from these clues.
The first digit is the answer when the third digit is divided by 2.
The second and third digits add to 7.
The second digit minus the first digit is 1.
R is a three-digit number: ____
I have never understood how to do this.
Determine the digits of R from these clues.
The first digit is the answer when the third digit is divided by 2.
The second and third digits add to 7.
The second digit minus the first digit is 1.
R is a three-digit number: ____
I have never understood how to do this.
Answers
Steve
Call the digits a,b,c left-to-right
a = c/2
b+c = 7
b-a = 1
we see that c=2a, so
b+2a=7
b-a=1
subtract to get
3a=6
a=2
Thus c=4 and b=3
R=234
Or, just working with the specs,
c must be even, since it can be divided by 2. So, R is one of the forms
1x2
2x4
3x6
4x8
Since the last two add to 7, R must be
152
234
316
Since 2nd-1st=1,
R=234
a = c/2
b+c = 7
b-a = 1
we see that c=2a, so
b+2a=7
b-a=1
subtract to get
3a=6
a=2
Thus c=4 and b=3
R=234
Or, just working with the specs,
c must be even, since it can be divided by 2. So, R is one of the forms
1x2
2x4
3x6
4x8
Since the last two add to 7, R must be
152
234
316
Since 2nd-1st=1,
R=234