2. Paint six sides of a cube with a side length of 3 cm red, then cut its length, width and height with two knives and cut it into hundreds of 27 small cubes. How many cubes are red on three sides, red on two sides and red on one side?
8, 12,6
Xiaoming and his brother came home from school at the same time. Xiaoming walks 80 meters per minute, and his brother walks 70 meters per minute. After leaving 1 minute, Xiao Ming went back to school and closed the window. Finally, Xiao Ming and his brother got home at the same time.
(1) If we ignore Xiaoming's window closing time, can we find out how many meters the school is from Xiaoming's home?
1120m
(2) If it takes Xiaoming 1 minute to close the window, can you find out how many meters the school is from Xiaoming's home?
1680m
After class, Xiao Dingding, Xiao Qiao and Xiao Pang play games together. Xiao Dingding and Xiao Qiao walked 30 meters from the two places where they met. Xiao Dingding's speed is 1.8m/s, Xiao Qiao's speed is1.2m/s. Xiao Pang starts with Ding Xiao, and his speed is 6m per second. When Xiao Pang photographed Ding, he turned and ran to Ding, and so on until Ding and Ding met. Can you find out how many meters Xiao Pang ran?
60 meters
5. A cuboid becomes a cube when its length is increased by 5cm, and its surface area is increased by160cm. What is the volume of this cuboid? 192
6. 199. 199× 198- 198. 198× 199
=( 199. 199×200- 199. 199×2)-( 198. 198×200- 198. 198)
=39.44 1-39.44 1
=0
7. 18.9× 178. 178+0.49- 17.8× 189. 189
=(20× 178. 178- 1. 1× 178. 178)+0.49-(20× 189. 189-2.2× 189. 189)
=3367.5642+0.49-3367.5642
=0.49