Question

How many two-digit odd numbers are there in all?
11) 44 (2) 45 (3) 47 (4) 90
2. In how many two-digit numbers does O appear?
(1) 9 (2) 10 (3) 11 (4) 12​

Answer 1

Answer:

1st question answer is 90

2nd question answer is 9

Answer 2

1.

To find :

• number of two-digit odd numbers

Solution :

• we write the two-digit odd numbers first:
• 11, 13, 15, 17, ..., 97, 99

• 11 is the first term and 99 is the last term
• common difference = 13 - 11 = 2

• let 99 be the nth term in two-digit odd numbers sequence

• then, 11 + (n - 1) × 2 = 99
• or, 11 + 2n - 2 = 99
• or, 2n = 90
• or, n = 45

Answer :

• thus there are 45 two-digit odd numbers.

2.

To find :

• number of two-digit numbers where 0 appears

Solution :

• the two digit-numbers where 0 appears are as follows,
• 10, 20, 30, 40, 50, 60, 70, 80, 90

• this is 9 in total

Answer :

• there are 9 such numbers