Number Thinking (1)( Week 18 Evaluation) 1. A prime number is a whole number that can only be divided by itself and one. What is the biggest prime number that is less than 140? 2. The product of two whole numbers is 45 and their quotient is 5. What is the smaller number? 3. Some toys are distributed to children. If each child is given 4 toys, 8 toys are left. If each child is given 5 toys, 4 more toys are needed. How many children are there? 4. A 12-hour digital clock shows time in digits with accuracy to seconds. What is the largest possible product of its non-zero digits? 5. How many pairs of prime numbers have a sum of 30 if the order of the numbers in a pair does not matter? 6. Which natural number multiplied by itself has a value which is closest to 61? 7. 1, 200, 3, 200, 5, 200, 7, 200, 9, 200, 11, 200, ...
In the sequence above, all even-numbered terms beginning with the 2nd term are 200. The odd-numbered terms are the consecutive positive odd integers. What is the difference between the 100th term and 101st term? 8. When the sum of two whole numbers is multiplied by the difference of the two numbers, the result is 77. What is smallest possible sum of the two whole numbers? 9. If 152 is added to one-third of a number, the result is 3 times of the number. What is the number? 10. A symmetrical number is a number that reads the same from either direction, e.g. 11, 121, 1221 are symmetrical numbers. What are the 3-digit symmetrical numbers that are divisible by 3? |