Page 2Calculation: Let the unit digit be x and tens digit be y According to the question, ⇒ 10y + x - (10x + y) = 18 ⇒ 9y - 9x = 18 ⇒ y - x = 2 It means that difference of digits of two-digit numbers is 2. ∴ Six cases other than (13, 31) are possible (24, 42) (35, 53) (46, 64) (57, 75) (68, 86) (79, 97) Mistake Points Here we cannot take (20, 2) Because 2 is not a two-digit number. Normally we do not write numbers from 1 - 9 as 01, 02, 03, 04, 05, 06, 07, 08, and 09.
When you reverse the digits of the number 13, the number increases by 18. How many other two-digit numbers increase by 18 when their digits are reversed? Answer Let the two-digit number be ab. When the digits are reveres (ba), the number is increased by 18. (10a+b) - (10b+a) = 18 a - b = 2 All such numbers that have unit's digit greater than ten's digit by 2. Numbers are (except 13) 24, 35, 46, 57, 68, 79. So. there are 6 other numbers. The correct option is B. Open in App Suggest Corrections 1 |