Question
A number consists of two digits. The sum of the digits
is 7. If 9 is subtracted from the number, its digits are interchanged. Find the number.Solution
Let the ten’s digit be x. Then, unit digit = 7- x . No.= 10x + (7-x ) = 9x + 7 No. obtained by reversing the digits = 10(7- x ) + x = 70-9x (9x + 7) - 9 = 70- 9x , or, 9x + 9x = 70 - 7 + 9, or, 18x = 72 or x = 4, so ten’s digit = 4 and unit digit = 3 Hence, the required number = 43.
More No. System Questions
- Select the number from among the given options that can replace the question mark (?) in the following series.
17, 18, 22, 31, 47, ___ - Which letter and number cluster will replace the question mark (?) to complete the given series?
LT6, KU12, IW24, FZ48, ____ - A series is given with one term missing. Choose the correct alternatives from the given ones that will complete the series.
57, 59, 56, 61, 54, ___ - Which letter-cluster will replace the question mark (?) in the following series?
RGV, UME, ?, AYW, DEF - Which letter-cluster will replace the question mark (?) in the following series?
NPQR, OORQ, PNSP, ____, RLUN
Relevant for Exams:
