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 135? 2. The product of two whole numbers is 576 and their quotient is 9. What is the smaller number? 3. Some toys are distributed to children. If each child is given 5 toys, 6 toys are left. If each child is given 6 toys, 6 more toys are needed. How many children are there? 4. A 12-hour digital clock shows time in digits with accuracy to minutes. What is the largest possible product of its non-zero digits? 5. How many pairs of prime numbers have a sum of 38 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 156? 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 200th term and 199th term? 8. When the sum of two whole numbers is multiplied by the difference of the two numbers, the result is 79. What is smallest possible sum of the two whole numbers? 9. If 323 is added to one-third of a number, the result is 6 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? |