the sum of the digits of a two-digit is 10. if the number formed by reversing the digit is greater than the original number by 36. find the original number. check your solution
Answers
Let the required two-digit number be 10x+y where x and y denote the digits of the number.
Sum of digits is given as 10. Therefore,
x+y=10⋯(1)
The reverse of the required number is 10y+x. [The digits are reversed]
Let us assume for convenience, the required number is greater than its reverse.
From the problem, the difference between the required number and it's reverse is 36. Therefore,
(10x+y)−(10y+x)=36
10x+y−10y−x=36
9x−9y=36
(÷9)⟹x−y=4⋯(2)
Solve equations (1) and (2).
x+y=10
x−y=4
⟹2x=14 [by eliminating 'y' from both equations].
⟹x=142=7
Substitute 'x' value in equation (1).
7+y=10⟹y=10−7=3
x=7,y=3
Now substitute 'x' and 'y' values to get the required number.
10x+y=10(7)+3=70+3=73
Now let's check whether the found number meets the required conditions:
Sum of digits = 7+3 = 10
Difference between number and it's reverse = 73–37 = 36.
Therefore the number is correct.
Let the two digit number be 10x + y.
y + x= 10 → (1)
The number formed by reversing the digits will be 10y + x.
(10y + x) - (10x + y) = 36
= 10y + x - 10x - y = 36
= 9y - 9x = 36
= 9(y - x) = 36
y - x = 36 ÷ 9 = 4 → (2)
(1) + (2)
= y + x + y - x = 10 + 4
= 2y = 14
y = 14 ÷ 2 = 7
(1) - (2)
= (y + x) - (y - x) = 10 - 4
= y + x - y + x = 6
= 2x = 6
x = 6 ÷ 2 = 3
10x + y = 10 × 3 + 7 = 30 + 7 = 37
Let's check.
3 + 7 = 10
The number got by interchanging the digits = 10y + x = 73
73 - 37 = 36
∴ 37 is the answer.
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