Question

A number consists of two digits whose sum is 9. If 27 is added to the number, its digits are interchanged. Which of the given steps is CORRECT to find the number?
Step 1 : Let the units digit be x
Step 2 : Then, ten's digit = (9 - x)
$\therefore$ Number = 10 x (9 - x) + x
$\Rightarrow$ 90 - 10x + x = (90 - 9x)
Step 3 : Adding 27 to the number 90 - 9x, we get 117 - 9x
Step 4 : Number with digits interchanged is 10x + (9 - x) = 9x + 9
Step 5 : 117 - 9x = 9x + 9
Step 6 : Therefore unit's digit = 6 and ten's digit = 3
Step 7 : Hence the number = 36.

• A. Only Step 4
• B. Both Step 1 and Step 2
• C. Step 1, 2, 3 and 4
• D. All steps are correct

Answer 1

Answer: (D)

All steps are correct

In given question we have to find the number.

$\Rightarrow$ To find the numbers $7$ steps are given.

$\Rightarrow$ All $7$ steps are correct to find the required number.

$\therefore$ Correct answer is option $D.$