2021年大联盟(Math League)国际夏季五年级数学挑战活动二

2021 美国"大联盟"(Math League)国际夏季数学挑战活动2021 Math League International Summer Challenge Grade 5, Speed Questions 1. (2021 ÷ 5) + (2021 ÷ 5) + (2021 ÷ 5) + (2021 ÷ 5) + (2021 ÷ 5) = A) 2020 B) 2021 C) 2022 D) 8084 2. Kirok the dragon has 2021 scales on his neck, 3031 scales on his wings, and 5051 scales on the rest of his body. What is the total number of scales on Kirok’s body? A) 1013 B) 7073 C) 10103 D) 100103 3. What is the remainder when (7 + 77 + 777 + 7777 ) is divided by 7? A) 0 B) 1 C) 4 D) 1234 4. Four out of every five dentists recommend HiGlo toothpaste. If I ask 100 dentists whether they would recommend HiGlo toothpaste, how many of the dentists will recommend it? A) 25 B) 30 C) 50 D) 80 ( 10 ) 学科网（北京）股份有限公司 5. What is the perimeter of a square that has an area of 64? A) 16 B) 24 C) 32 D) 64 6. 4 × 5 × 101 = 1010 × ? A) 2 B) 20 C) 101 D) 1010 7. Each angle of a rectangle is ? degrees greater than each angle of an equilateral triangle. A) 30° B) 60° C) 90° D) 120° 8. It is 2021 hours after midnight. What time is it? A) 5 AM B) 7 AM C) 5 PM D) 7 PM 9. If 20% of a number is 50, what is 40% of the same number? A) 30 B) 60 C) 100 D) 150 10. As he rides, Sir Reginald von Prime is going to plant a flag every time the total distance he has ridden is a prime number of km. How far will he have gone when he plants his 11th flag? A) 23 km B) 29 km C) 31 km D) 37 km 11. The greatest common factor of 43 × 52 and 53 × 72 is A) 5 B) 52 C) 53 D) 55 12. How many 2-digit odd numbers do not have 3 as either digit? A) 32 B) 36 C) 40 D) 44 13. My average score on the 3 tests I’ve taken so far is 85. What score do I have to get on the next to raise my average score to 88? A) 94 B) 95 C) 96 D) 97 14. Nan knits new tops for newborns. Today she knitted one more top than yesterday. The number of tops she knitted in the two days combined could be A) 12 B) 23 C) 34 D) 100 15. 8 dozen socks = ? pairs of socks A) 24 B) 36 C) 48 D) 96 16. A boy is in line with 30 people behind him and