| Question | Answer | Explanation |
| How many three-digit odd numbers are there? | 450 | There are 900 three-digit numbers starting with 100 and ending with 999. Half of these are odd numbers and half of these are even numbers. |
| How many two-digit even numbers are there? | 45 | There are 90 two-digit numbers starting with 10 and ending with 99. Half of these are even numbers and half of these are even numbers. |
| Which of the following is the smallest odd number: 989, 567, 456, 322? | 567 | The even numbers are 322 and 456. The odd numbers are 567 and 989. So, the smallest odd number is 567. |
| Which of the following is the greatest even number: 2046, 2406, 2640, 2604? | 2640 | 2640 > 2604 > 2406 > 2046. |
| In how many ways can 48 be expressed as the product of two even numbers? | 3 | The 3 ways to express 48 as the product of two even numbers are 2 × 24, 4 × 12, 6 × 8. The fourth way is 3 × 16, but 3 is an odd number. |
| Which is the 14th odd number after 192? | 219 | The next odd number after 192 is 193. The 13th odd number after 193 will be 193 + (13 × 2) = 219. |
| Which of the following numbers when multiplied by 5 gives an odd number: 88, 76, 97, 66? | 97 | When a number is multiplied by 5, it gives a number with a 0 or 5 in the units place. Only an odd number when multiplied by 5 gives an odd number with a 5 in the units place. |
| If the sum of two odd numbers is divided by 2, what will be the remainder? | 0 | The sum of two odd numbers will always be an even number. If an even number is divided by 2, the remainder is 0. |
| What should be added to 198 to obtain the fourth odd number serially after it? | 7 | The fourth odd number serially after 198 is 205. Note that 198 + 7 = 205. |
| What is the sum of the odd numbers between 30 and 40? | 175 | The odd numbers between 30 and 40 are 31, 33, 35, 37, 39. Their sum is (30 × 5) + (1 + 3 + 5 + 7 + 9) = 150 + 25 = 175. Note that 175 is simply 5 times the middle number (i.e., 5 × 35 = 175). |
| What is the sum of the sixth, the seventh and the eighth even numbers after 70? | 252 | The sixth, seventh and eighth even numbers after 70 are 82, 84, 86. Their sum is (80 × 3) + (2 + 4 + 6) = 240 + 12 = 252. |
| What is the difference between the 23rd and the 26th odd numbers coming after 25? | 6 | The difference between consecutive odd numbers is 2. Therefore the difference between the 23rd and the 26th odd numbers will be 2 × (26 − 23) = 6. |
| What is the difference between the sum of the even numbers and the sum of the odd numbers between 20 and 31? | 5 | The even numbers are 22, 24, 26, 28, 30. The odd numbers are 21, 23, 25, 27, 29. Thus, the answer is
(22 + 24 + 26 + 28 + 30) − (21 + 23 + 25 + 27 + 29)
= (22 − 21) + (24 − 23) + (26 − 25) + (28 − 27) + (30 − 29)
= 1 + 1 + 1 + 1 + 1 = 5. |
| What is the difference between the greatest four-digit even number and the smallest four-digit odd number? | 8997 | The greatest four-digit even number is 9998. The smallest four-digit odd number is 1001. Their difference is 8997. |
| Using each of the digits 0, 5, 7 once only, how many three-digit odd numbers can be formed? | 2 | The 2 three-digit odd numbers that can be formed are 507 and 705. |
