Question

5. A two digit number is such that the
sum of its digits is 4. if 18 is added to
the number, its digits are reversed. Find
the number . (Non-anonymous question )
(5 Points)​

Answer 1

Answer:

Let digit at 10

′

s place =A, unit's place =B

∴ Number =10A+B

After adding 18, it becomes 10B+A

∴10A+B+18=10B+A

∴9A+18=9B - (1)

We have A+B=4 (given)

∴9A+9B=36

∴9A−36=−9B - (2)

Adding (1) & (2)

18A−18=0

∴A=18,B=3

Answer 2

Answer:

13

Step-by-step explanation:

Let the two digits are x and y

Hence the number will be 10x+y

According to the question, sum of digits is 4

=>x+y=4________i

if 18 is added to the number its digits are reversed

=>(10x+y)+18=10y+x

=>10x+y-10y-x= -18

=>9x-9y= -18

=>9(x-y)= -18

=>x-y= -18/9= -2_________ii

Adding equation i and ii

x+y= 4

x-y= - 2

¯¯¯¯¯¯¯¯¯¯¯

2x=2

=>x=2/2=1

Putting x's value in equation i, x+y=4

1+y=4

=> y=4-1=3

Therefore the two digit number is

10x+y=10×1+3

=10+3

=13